Easy heroes for new players

Tanky hero you say, well I'd recommend Tidehunter, he's a game changer and also a good tank.

Dragon Knight is also a fairly easy tank to start with.

Axe is a good tank, he's really effective, I don't consider him difficult at all.. he's medium so to say.

Nearly any str hero can be considered as a tank, but if you are looking for easiest one I can suggest - Centaur Warrunner as he have tons of hp, Bristleback as he is very annoing and have great dmg reduction, Lifestealer is just ******ed rightclicker, Skeleton King with 3 passives and 2 lives when you fail in battle, Sven have great aoe stun and his dmg just doubles after using ulti, Tusk don't let his enemies get away from his team and Tiny is big nuking rock with annoying stun and throws team mates at enemies.

Also Tiny/Tusk + Centaur Warrunner is great combo, as Tiny and Tusk let Centaur get close to enemies, land his stun and kill instantly.

Well if you want to try an easy, and somewhat tanky carry, may I suggest Viper. He's very easy to play and his passive makes him durable.

Axe is a good tank, but you need to know how to jungle with him. You won't need to every game, but sometimes it's necessary. The same applies to heroes like Lifestealer and Skeleton King, although they are more commonly laned.

Playing tankier heroes like Tusk, Centaur, Tidehunter, Bristleback require you to gank. Farm is wasted on these heroes, and they get their levels and gold from ganking and fighting.

My advice is, if you can't gank nor jungle, then play a tanky carry. If you want to be tanky from lvl 1 to 25, then you only got a few options: DK the best among them.

Spectre is considered a very tanky hard-carry thanks to her damage block. And IMO Medusa
tankiest carry in the game, tho hard to use correctly, impossibe to kill good medusa player.
Pudge is considered one of the tankiest heroes in the game because of his high STR gain and flesh heaps, but you have to learn the hook.
There are lots of tanks in the game: Chaos Knight skeleton king doom bringer necrolyte( very tanky for an INT hero tho 5 sec cooldown heal/nuke and usually builds a Rod of Atos.
If you want tank items you can find them under armor in the shop.