Well, I've often kind of wondered if the physical power of animals is overestimated. The reason is that you just hear wild stories that sound ridiculous for mammals. I remember reading on a site, one guy thought a chimp (IIRC these weigh 90 - 180 lbs) could lift 600 lbs on one hand with absolutely no effort. I believe a chimp could rip an average guy's arm off, but I'm pretty sure that lifting 15 - 20 times your own weight is something only insects and arachnids are capable of.
600 is not 15 times a chimp's weight. More like 6x. Chimps are extremely strong, easily capable of ripping someone to shreds. Just google "chimp attack images" to see some real horror shows.
The bigger issue is not how strong the chimp is, but the mechanical (dis)advantage of a chimp's long arms in trying to life a weight.
A better, fairer test would be the ability to pull an object, or to rip an object apart.
Comparing strength requires comparable tests.
Obviously an elephant is much stronger than a human, but I can easily out do any given elephant in chin ups.