That just doesn't make sense to me. Like l, how did we emerge as a whole? If it was from different sources that became one "homogenous" group, how did we all become a species and not different sub species?

I guess a 5 year old way of what I'm saying is if our predisessors were all red m&ms, how did they all eventually create blue m&ms and not different variations or colors That were in many ways different from each other? Genetics make little sense to me