Do you believe in the evolution of human consciousness?

No. I believe, instead, that each of us as individuals should strive for the goal of attaining enlightenment, which can be accomplished in this lifetime. This is a far cry from anything that "evolution" can promise. Once that goal is accomplished, then each of us (as Buddhas) will be conscious of all that ever was, all that is, and all that ever will be. Better than merely being "conscious" of all that, we will acquire the ability to change all that. But, strangely enough, we will have no burning desire to do so. Compassion, yes; burning desire, no.

Consciousness is not the same as Buddha-nature; "consciousness" is too small a word.

As to your last question: "And if not, do you feel we are different now than we've been in the past?" - I will say this: I don't care much for the "we" part. "We" never attained Buddhahood. That's what individuals attain based on strenuous and persistent individual practice. Like Sisyphus, I've been pushing that boulder up that hill - in the name of seeking enlightenment - for many lifetimes. And so have you - or many of you, at any rate. Only to backslide.

The trick is to find the breakthrough. But that's no trick at all. The key is to keep practicing.