The heroes are vastly different from one another, and are very different in terms of skill ceiling and floor. Meepo and Invoker are considered the two most mechanically demanding heroes, and should never be played by a new player.

Contrast this with Bristleback, whose gameplay consists of right-clicking an enemy and spamming W, then turning around and running away if they fight back too hard. There's also Sven, whose gameplay consists of using a stun ability, right-clicking an enemy, and they're probably dead. Axe, whose gameplay consists of running in and hoping people are stupid enough to hit you, and using your taunt ability to force them to do it if they aren't.

Finally, there's Sniper. You right-click enemies. That's about it. He has a slow and a long-range nuke spell, but if you've right-clicked an enemy you're at least helping.

Of course, higher skilled matches change things drastically and more complex teamwork and ability use is needed at those levels, but for a new player, these heroes are all very simple and straightforward to use.