one of Charles Darwin's biggest influences for his theory on natural selection would be Jean Baptiste Lamarck because he was one of the first to propose that humans evolved from a lower species through adaptations over time. some of his theories weren't correct but even then Darwin adopted his ideas as his own.

Lamarck published a series of books on invertebrate zoology and paleontology which on one the series states his theories on evolution. which represented a great advance over existing classifications; was the first to separate the crustacea, arachnida, and annelida from the insecta. His characteristics of the mollusks was so far ahead of anything else before it.he also concluded the work of schleidon and schwann in cell theory stating that "nobody can have life if its constituent parts are not cellular tissue or are not formed by cellular tissue".

http://www.ucmp.berkeley.edu/history/lamarck.html

his evolution theory was rooted in the idea that life started out as simple and built up until it turned to a complex human form. he was impressed by how the animals he experimented with shared some similarities with it. these things made him think that life was not fixed he strongly believed that each species had to adapt to its environment.

without this theory darwin wouldn't have been able to develop his theory of natural selection as it states Darwin adopted his theories as his own with a slight difference in Jean's mistakes.

darwin was a respectable man for the church and used the bible as one of his explanation it caused a great hullabaloo with the christian church.