Horsepower is a bi-product of torque... torque is work...horsepower is work within a certain amount of time...that time is RPM
I kinda compare it to watching birds fly. If you watch a big Hawk, there wings dont move real fast, but there long & forceful, gets that large bird moving & moving fast.
Than look at say a humming bird....there little wings are just screamin fast. Thats my way of comparing.