For human I would suggest these heroes in this order,
Honestly 5 is overkill, even 4 might be, but Vallari and Tiadrin are extremely underrated and I very highly suggest them even if someone else disagrees. Merry Christmas!
I mostly agree with this. Jaques and Elena are the most important heros in the game by far. Jaques is overtuned (busted) damage, and Elena has incredible utility in combination with Jaques for bronze hitting walls (use recall to remove a gold troop from the field, which allows you to hit the power req). I'd put Tiadrin at 3 since she does AOE damage to the entire enemy force with ret aura, and heals your own heros, preventing enemy morale boosts. Both are passive and require no inputs, so you can focus on other abilities.
In my opinion, these 3 should be owned by every race.. Jaques (busted), Elena (insane utility), Tiadrin (strong passive damage + auto heals... does her thing without requiring your focus). After the top 3, its not as obvious what to take. You would probably want Yip for the tail wind auto cast, and I would personally take Cleo for the high impact ultimate. Rose is an option due to general strength and the web dropped on enemy units is high impact and lasts the entire fight.
All of that being said, when it comes to leveling, heros such as Avalon and Vega are top top priority for buffing human units and maxing Favor of the Sun God. Humans actually have a very good spread of heros from the free heros that are very important to their success.