If you mean how horses helped humans in history check out this website : http://www.equestrianmag.com/article/history-horses-humans.html
Sea Horses are small sea creatures that can be pets. They live in reefs which does help the food cycle/life cycle but they don't do anything for humans and I think the world would go on if their were no sea horses! (: Does that answer?
Most humans treat horses well, but some humans (unfortunately) abuse them.
A good majority of horses do trust humans. These are horses that are treated fairly and have owners who make themselves the 'herd leader' and can prove that they will be fair, just, and protective of the horse. However not all horses will trust humans and not all humans are to be trusted, horses instinctively know this.
In horsepower? less than 1 hp I suppose, as humans are less strong than horses that's probably not too helpful.
monerans are helpful to humans because it is bacteria and bacteria helps humans by making milk yogurt
An aolovera plant is helpful
Horses do have ears just like humans.
humans depressed humans are less effective
Why yes, but humans look nothing like horses. Horses get the same sicknesses as humans do and they can get arthritis. Hope that helps
Technically yes it can, so long as it is a strain that is infectious to both horses and humans. However, horses are pretty resistant to tuberculosis.
no
horses have babies just like humans, exept they're horses, of course