Answer me this: When should a player start considering what character to be good at?

Killing fast and efficiently you say... Hmm, you could try Pudge maybe? He's really useful too, catching fleeing enemies, hooking enemies so your team can kill them, save teammates, etc.

You just described a whole wall of heroes, as Hades said, maybe you need a change in heroes. Getting yourself well rounded in heroes isn't ever a bad thing :)

That actually narrows it down to about nukers and carries...maybe Lycan?

I have the same amount of experience as you do,(200 games), and I have played every hero Dota 2 has to offer but about 10.

Anyway, Kunkka is a good pick if you like a carry useful in teamfights. Faceless Void can work, too.

I'm personally favored towards semi-carries and nukers/gankers, because I really don't like farming all game like void or PA, but I still enjoy playing carries occasionally.

Personally, I try to play new heroes as much as possible, while in between new heroes I go to my old ones just so I stay fresh with them. Pubs suck because of randoms and people that don't like team chemistry at all, which most of the time forces me to play a certain hero or type of hero. Eventually I just got the hang of it. I mostly play supports because no one likes to play them and I do. ES, Disruptor, and Rhasta for life! those three are my main men and my teams do better overall when I play them.

Additionally, like hades said, find friends. There are people in the community that are willing to group up and play. I made several random friends through pub matchmaking and now I pretty much play with at least one other person. Makes life and games so much easier.

Well for any hero you must master the basics then the hero, master efficient/smart farming for carries, warding/babysit/etc for general supporting, grow some balls for initiators.

Mastering the basics is the best IMO, on some days I random every time even if I rarely played that certain hero, i.e Chen...

This is definitely true for rolls in team composition. Glayde said it pretty well but I will expand a little bit. You could try playing the roll that you have the most fun with whether it be hard carry, initiator, jungler, nuker, or support. Once you find out which roll is the most exciting for you (or comes the most naturally) you can then learn to play all the specific heros in that roll so that if you do decide to play on a team with defined rolls you will be able to play them all.

I tend to do what Dirtgrub does, I play all the heros but I always go back to the ones I love or the ones that will compliment my team composition the most.

Hope that helps!

In my opinion, with experience of the dota meta game, you should be able to function with any hero on a competative level. What will seperate you is the ability to play versatile and situational when the need be. So choose your hero based off of what the team has/ needs. I find that It is best to let the other people play what they are comfortable with and I play what we need. Whatever the situation calls for.

Of course I have some favored heroes... but if the team doesn't need them I definately don't play one. Case and point, if you only play Void, and you are considered the best void player in the world, you probably are not going to win in a game where the rest of your team picks all melee carries with no cc :(. Being versatile allows you to build around others... not others build around you. This will get you more wins then just playing.

I have played plenty of games where I had to switch my build from a carry like Void to getting a sheep stick with him Like WTF why would someone ever do that... well i was having issues with chrono then this audacious enchantress would sit outside of crono and peg me to death. Well I saved face and scored triple kills the rest of the game because I sheeped her.