First off, should they have done this? Obviously not, only the people without empathy would argue that, but let’s face it, we’re not talking to the sociopaths anyway.^^
That being said, we can barely influence how others treat us, so let’s look at what you can change, because the truth of the matter is that games with toxic people are fairly rare. I think not a single one of my 20 comp games this season was toxic, and only 1 or 2 of the 40 games last seasons were. So it’s possible, but how?
First up: level 25 just isn’t enough. You should know all the maps (from both sides if applicable) and all the heroes. Not by heart, and you don’t have to know where every single health pack is, but you should at least have a sense of direction with at least some knowledge of the different angles of approach. As for the heroes, you have to at least know everyone’s ultimate, their effecitve ranges, their roles. Otherwise, how do you know who to target and when?
Then there’s your hero pool. Sure, DPS heroes are very easy to learn and you don’t require much knowledge, but you should acquire some versatility at least. Generally speaking you should also assume that other players have more experience than you, so they might actually know better whether or not your pick is effective against a certain enemy composition. Unfortunately, many people will just use you as a scapegoat and tell you to swap even if you’re on the best option already. Getting knowledge about who is effective against what takes quite a bit of time, but there are a few principles to adhere to: Pharah is countered by hit scan, Snipers are countered by shields, mobility heroes are countered by crowd control, Moira is good at healing people that group up, Zen is good at healing flankers, etc.
Tanks and supports require more game knowledge and awareness, so you will have a harder time with that if you lack experience. On the other hand, your impact on the game will be larger and people generally like it if you play roles they don’t like to play (and most people main DPS, so it’s always hard to find the tanks and supports).
Comms are an important factor in controlling your environment. If you’re silent and don’t even listen to voice chat, that can quickly escalate. Setting a positive tone can have a huge impact on your team - just by talking and not just going on an ego-trip, instalocking your main, but instead asking what the team thinks they might need. That’s where it helps to have a deep enough hero pool to facilitate all of this. Obviously, comms are something people shy away from when they feel that they don’t have much to add, and you will at this point in time, know less about the game than others - so I understand that you can’t be as proactive as veterans might be.
And then… then, there’s the cesspool argument. At level 50 you will be a lot better than at level 25, unless you don’t pay attention when you play or always blame the others for anything bad. If you play at 25, you will more likely get placed in Bronze, where everyone else is just as bad, and since they are bad, they probably are too bad to realize when they make a mistake. They are probably too bad to see, if you do a good thing. They are probably bad, because they like to throw blame around, so it’s no fun playing with them.
So take your time to get better - learn the maps, learn the heroes. Play against bots until you know all the maps and if you want to try out heroes in a chill environment. Play arcade if you want to improve in certain areas: FFA DM if you want to practice your aim (which is a bad idea, because aiming just comes naturally anyways), 3v3 elims if you want to practice a certain role (Roadhog - Zarya - D.Va for off tanks, Rein - Winston - Orisa for main tank, etc. Use the LFG feature to get a balanced group with 1 tank + 1 healer + 1 DPS), Mystery Heroes if you want to deepen your hero pool and learn about what counters what without studying, Mayhem if you want to test your ults (D.Va comes to mind), No Limits if you really, really want to learn more about the mechanics of a specific hero in weird conditions.