Before Darwin, had much thought been put into the relatedness or similarity between humans and other apes?

So I know a lot more about Philosophy than History, but I think a look at Arthur O Lovejoy's The Great Chain of Being might be helpful. Essentially, since Plato there has been a hierarchy of Being, starting with the basest material being rocks, dirt, then moving on to basic plants and animals until reaching man, then the heavens/ celestial beings and finally arriving at a self caused, absolute God. This was used as a long running concept from Plato right up into the 17th and 18th century to explain the seeming gradation of non living to living matter and from matter into spiritual substance(in which man is unique insofar as he/she is is the only being straddling this chasm). But to pull this back into focus, this is called by Armstrong the Principle of Plenitude. Along the lines of The Ontological Argument the argument goes

God is that which is good
To exist is better than to not exist
God cannot withhold existence from something that can exist without breaking any precepts of logic

So if a man and a monkey exist, it seems there would be a gap of a possible animal, a chimp. If this gap isn't filled it suggests a lack of perfection in God. If interested I'll try and find the book and give a better version of the arguments made and(very importantly of course) a short description of what he says about major thinkers. I remember him talking about Plato of course. Aquinas, Origen, Spinoza. That's all I can pull off the top of my head.

TL;DR, The West since Plato has understood the gradations between animals to belong to God's perfect expression of every possibility of his will.