There is much more to early ideas of evolution than just Lamarck. The
thinkers of the French enlightenment are particularly interesting. Diderot's
ideas in the mid 18th century were startlingly similar to Darwin's natural
selection in its major aspects. Diderot did retain a bit of the old notion of
vitalism, though. His contemporary, the Baron d'Holbach, dispensed with even
that in his "System of Nature" of 1770 (called "The Atheists Bible" by his
contemporaries). None of these were scientific theories, however (as
opposed to metaphysical, philosophical views).
The notion that modern humans had evolved from an earlier form was already
well established in ancient times. Plato, Aristotle and Lucretius are usually
particularly mentioned in regard to this. More modern ideas of human
evolution gradually developed in parallel with the scientific study of anatomy
and geology in the 18th and 19th centuries.