You should take endocrinology--you'd love it. Actually many of our biochemicals are manufactured in stages, e.g, cholesterol to progesterone to 5-alpha dihydrotestosterone to testosterone, etc., etc. For some of these intermediary stages function has been found. For others it has not been elucidated. These are some intermediary stages in neurochemistry that are so short-lived that neuroscientists are sure they are not identifying them all. Then there are the neuoropeptides secreted by the hypothalamo-hypophyseal axis. One such has been isolated long ago (adrenalcorticotropic hormone) but still today even the best methods still produce a "contaminated" product that has other (unidentified) neuropeptides present. These contaminants are bioactive.
Giving a long list of true facts does not prove evolution. The problem is that there are many essential processes in life which are quite complex and which do not work at all without numerous different parts working together. This is an impossibility for gradual evolution since the different parts would be useless until all the parts were present - and working together as a unit. More important, the numerous systems in an organism all have to be present and work together also. Can you live without a heart, without lungs, without a brain, a stomach? There you have the problem for evolution - systems within systems within systems - all having to work together and be present for life to be possible.