General Discussion^ What am I doing wrong

You're playing out of meta heroes (mostly)

High amount of deaths for cores suggest you die too much mid game and have a problem with over extending with a lead.

Bro, personally it involves all the factors: teammates, meta, senseless decision making in-game and hero pickings. But the thing I can advise you is:
1. to have the mentality of "What can I do to make it better?", "What things I didn't do to cause the losses?", instead of having a blame mentality.

2. Also, willing to accept any roles; especially if your in 2k - 3k mmr where almost everyone wants to be a carry, in this situation take with pride the hard support role. Supports is the one who wins games, they are the ones carrying the heavy load early to mid game. They are the one carrying the Cores in early games. For me, support is the hardest one to play, since you have to have all the facets to secure that your lane is not losing. You have to make sure that you have proper vision; map awareness is also a key.

3. I advise you also to be vocal with your teammates on what to do. Be proactive during the game by always reporting missing heroes; and also make a calculated prediction on enemy heroes' position in the map. Be the leader if no one else does.

4. Also, check your network connection. Check pings before going to a match, it really is a very material factor why you will lose the game.

5. Make sure that you are playing without distraction.

You need to play safe, play escape heroes, or Mirana only to stop ur losing habit.

idk, i think u did well; just unlucky

You need dota plus bro

Greedy af and not objective based (not enough).

But since most of them are party games, it is not entirely your fault that you lose (you and your team fault).

I suggest learning the concept of lane pressure and "space". To improve your party and solo games.