This is like saying the pre-socratic Greek philosophers "discovered" the atom. Their "discovery" was just vague speculation. Darwin didn't just say "evolution happens", he demonstrated it. Before him no one else demonstrated it. Surely, a lot scholars speculated about evolution long before Darwin. One of them was Erasmus Darwin, Charles grandfather. But that misses the whole point: no other scholar was able to embed…
It's also interesting to note that Darwin's theory had to be reformulated several times before it could match contemporary data. I'm talking specifically the Modern Synthesis (Darwin + Mendel) but also more contemporary syntheses such as Koonin, Huneman & Walsh, etc. [1]
[1] https://en.wikipedia.org/wiki/Modern_synthesis_(20th_century...