If you were to debate Lamarck today about his theory, what core concept in biology would you rely o

Lamarck was strong on the inheritance of acquired characteristics but may have placed too much emphasis on this happening in a short period of time like perhaps a few generations. Charles Darwin showed that something similar happened by natural selection of varieties that were favorable to the survival of the species and the extinction of varieties that were not adapted to the natural conditions, but that this process took time but in the end, an organism can develop more favorable traits like mankind when he/she developed the apposable thumb which was an innovation that allowed him to progress from his ape ancestors.