The other interesting things about axolots is they have what is called "neoteny" basically meaning the organism COULD proceed to adult form but never does - the natural axolotl is sort of a half-metamorphized creature for life, similar to a frog halfway through the tadpole->frog changes. You can induce the transformation with thyroid-type hormone stimulation (thyroid / TSH), which results in a salamander - essentially resurrecting this ancient morphology not seen in this world for a long time. Then the regenerative capabilities (seen in other amphibians as well) you can think of that as, "child humans heal better, what if the human is a child for life" in simplistic terms. There are also tradeoffs the organism makes i.e. ability to reproduce at a younger age (reproduction evolutionary win), and notably, the histology and cellular structures are simplified and less complex than say mammals, thusly making body parts easier to regenerate. It's also notable that amphibians have massive genomes, the axolotl being 10x the size of humans! - but with about the same number of genes, why? Well if mutations occur at random positions and you have ~10x more non-coding junk DNA, you've just lowered the frequency of mutations hitting coding genes, they are more likely to hit "safe" non-coding parts. All of this is important because if a mutation slips into the regenerated limb -> cancer, so we're de-risking mutations by having a massive genome https://www.mdpi.com/2221-3759/9/1/2