I am not arguing just to argue, I am making my point that animal research has huge limits which calls for caution in jumping on the bandwagon with too much enthusiasm. .
There are already very different outcomes or reactions at the same compound between two humans, leave alone between different species.
Test mice for testosterone and they would respond amazingly well to almost anything, a very different story than with humans basically only responding to exogenous testosterone.
As you say aspirin is used by millions of people all over the world since quite a while and willow bark since at least 2400 years ago, if you like to know what I think is that it is unlikely that it will extent human life significantly or by now we should already noticed it.
As I wrote it is probably smarter and possibly more effective to take willow bark instead of aspirin but as a life extension drug I am not buying it yet.
About its toxicity:
"Conservative calculations estimate that approximately 107,000 patients are hospitalized annually for nonsteroidal anti-inflammatory drug (NSAID)-related gastrointestinal (GI) complications and at least 16,500 NSAID-related deaths occur each year among arthritis patients alone." (Singh Gurkirpal, MD, “Recent Considerations in Nonsteroidal Anti-Inflammatory Drug Gastropathy”, The American Journal of Medicine, July 27, 1998, p. 31S)
and
https://en.wikipedia...pirin_poisoning
...just as examples.