Platypuses, Tapeworms, and Deformed Young

Yes, yes, I know...it's been waaaay too long since I posted last.
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"The platypus is one of nature’s success stories because its structures are well
adapted for its lifestyle and habitat." - Nelson Biology 11 textbook

When I first read that, my first thought was "whaaa? that sounds so dumb!"

Yes, dumb. I immediately thought back to the previous chapter, where one of the questions had been about the parasitic tapeworm's "undeveloped" digestive system - whether or not it provided an "evolutionary advantage". (Also explained in the textbook is that its simple digestive system allowed more room for reproducing. Reproducing on a large scale is important because, like fish, out of thousands of eggs only a few survive) The obvious answer from an evolutionary perspective is "No!". But if you think about it, aren't the tapeworm's structures "well adapted for its lifestyle and habitat"? (Except instead of adapted, I would use the word "designed" - it is very well designed for its lifestyle and not lacking anything.) Shouldn't it too be considered "one of nature's success stories"?

Evolution confuzzles me to no end because it is sooo full of contradictions. For an apologetics assignment, I did an internal critique on an article that I found. The article was talking about how mammals kill or abandon severely deformed young, but it seemed that "ancient humans" did not do the same. Since animals do kill or abandon severely deformed young, how is evolution even possible because it would have required millions of severely deformed young to have been born? And if they didn't kill deformed young "back then", why do they do it now?

The only explanation I can come up with for why people choose to ignore the problems with evolution is because they "suppress the truth by their wickedness" (Romans 1:19)