First of all treat it as a totally different kind of moba to avoid conflict between beliefs because the game is totally different from league. Unlike league where everything is fixed like roles, items and its timings, objective and its timings everything is situational in dota. Start from here:

Pure Basics Of Dota:https://youtu.be/9Szj-CloJiI

Advanced Basics of Dota: https://youtu.be/u0rYxCVRrUM

I want to copy paste something here which may be in detailed as these are the answers i posted to some new dota players switching from lol to dota:

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I wrote to help another fellow league player switching to dota 2(some may be irrevelant to your question but still super helpful and necessary for any league player transitioning to dota2 to understand the dota2 so i kept it anyway + i am too lazy to edit :P): Now coming back to your question, carry are those heroes who are mostly focused on damage dealing in teamfights, to structures or objectives like roshan. These heroes require farm to perform and do their job ( farm in the sense they need gold to buy items because they are very item dependent to do high impact in the game). Support are these kind of heroes who are either focus on protecting your heroes or locking down enemy heroes making them useless for some time using cc in a very basic sense, but some support haves high impact dmg skills in teamfights too. Basically supports are these kinds of heroes who dont need much farm( very little gold needed) to have high impact in the game. They dont buy costly items and their skills scales automatically with levels and talents so items in supports are more focused in saving your teammates and yourself in fights( again this is dota everything has exceptions and literally anything and everything can work so take this as a very basic concept when starting. The higher ranks you go the weirder strategies you see.)

About your agility, strength and intelligence types, they are totally different things. In LOL you have two types of scaling either it AD(attack damage also known as physical) or AP(Ability Power also known as magical) which makes scaling in lol static and easy to understand. But dota has these three types which makes scaling much more dynamic as all three types of stats can give you scaling doesnt matter you are agi,str or int type hero. So basically in learn this, Dota is a very creative game in the sense everything and anything can work and your creativity is your biggest strength in this game. Every hero can play in every position if you know what you are doing and can make it work. So keep yourself very open minded while playing this game, its a game of experimentation and creativity.

And about items, follow the guides at beginning, mostly you buy the items according to your main attribute( ie str,int or carry) but dont be suprised to see str items build in agility heroes or stuffs like that. Items in dota are not focused on scaling but solving your problems and making your life easier. And you may have already noticed that in dota there arent 3 types of dmg scaling items like AP dmg, AD Dmg or True Dmg( called pure dmg in dota) like league or other mobas. There are items that give you +dmg and thats it. These one item gives you dmg whatever type of dmg you do physical, magical or pure. So item building is much more complex in dota because it has dynamic scaling so you need to try heroes in the try tab and buy different types of items and check how it effects stats themselves. That way you can experience and discover firsthand how scaling works in the game and how is it different in each hero. And about

PS if you wanna learn of positions in dota which will help you clear your doubts more and wrap your head about heroes and their positions and thought process of each positions watch this. Again in dota , i repeat again anything and everything can work and nothing is fixed so even after watching these vids dont just follow them blindly but instead your your own logic, reasoning and creativity to form your own positions and play according to that. Everything this game from positions to playability to meta is made by the community not the devs, the devs say whatever you do the end goal is to take the enemy ancient before other team does. Whatever bullshit shenanigans you do to reach there is not our problem, if it works it works. So just take ideas from the two videos i mention below. Also one is the very beginner way of thinking about roles while starting while other is more high ranked advanced way of thinking about it.

Basic Thought Process about Competitive Positions In Dota:https://youtu.be/3qEIQCffp0I

Advanced Thought Process about Competitive Positions In Dota:https://youtu.be/FI8bP-YVZyk

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The thing is you cant go in dota with the mindset of " i am high ranked in LOL i am gonna start smashing from my 1st or 10th match". Lets face it you are gonna suck the first 100 matches and gonna get completely stomped. Only after 100 matches you will see little progression. You only start getting the grip of the game from 1000 hours above. Then you can look to improve. Because tbh, DOTA is not a harder version of LOL as most LOL players think but its completely a different game, you have to leave behind the lol knowledge because everything is super complex in dota eg there are no fixed roles, every hero can play every role, a single hero doesnt do full physical or magical dmg but you have to manually look through skills and right clicks to see what type of dmg it does, items have actives which turn matches and items,heroes and stats arent straightforward as there is no only AD or AP scaling which is static scaling but the hero attribute type ie Strength, Agility or Intelligence brings dynamic scaling which makes grasping the exact scaling with items very tricky.

But the main difference when you play DOTA and why are you not being able to win teamfights and play the game is because LOL is focused on micro based teamfighting where its all about mechanics to win fights ie you have to outplay your opponent using micro to win fights. In DOTA its exactly the opposite, DOTA is focused on macro based teamfighting where its about using all of your avaliable resources to outsmart your opponent and turn tables in a fight.

I come from Vainglory(its like LOL) to DOTA so i can say that yes it eventually does get better but you need to be persistent and go with the mindset of i am here to learn not to win until you get te basic grasp of the game. Dont ever think that you will start stomping DOTA after your 10,100 even 1000 matches because DOTA doesnt work that way, your mechanics alone cant carry you to stomping people, you need to think and play teamfights like a chess and try to outstrategize opponent in teamfights. Its all about macro decisions in DOTA.

Rest whatever you wanna learn you can just search up in internet and learn from google, youtube etc etc. https://dota2.fandom.com/ is a great place to learn how the game works and stats behind the game.

Looking for Dota YT Guide Channels? Here is the list:

ProGuides Dota, Gameleap Dota, Gamerzclass Dota, Dota 2 tips, Pvgna, Play Like Gosu, DotaCinema, Docwel, Script, DATOHLEONG, xuisoko, BananaSlammaJamma, PurgeGamers, Jenkins, Rawdota, Henry Dota 2, DotaDBowie, Alexander Coccia, Good Boy Guides, Erick Wright, Mr Bean Dota, NizeYourself, ZQuixotix, Bren Dota, Paul Normington, GamePointz, DEFYED Gaming, ShaniDota,Krevs Dota,Meric, Xeonus,Parm,Plumtown,Wagamama etc.