Seeing the up votes and down votes in this thread, I realize this is an unpopular "opinion" but the flowers didn't necessarily evolve to look like hummingbirds specifically. That many people see it as looking hummingbird-like is more a reflection of the human mind's ability to find patterns and connections even when they don't exist. It's interesting and pretty for sure, and definitely a curiosity.

Same thing for the "monkey orchid". You see a monkey because the flowers are photographed at an unnatural angle and forced perspective, the photos online where the effect is most visible are the ones with lots of compression artifacts and generally poor quality, and because of the power of suggestion. If you saw these in person (without prior context of the photos), there's a good chance you wouldn't even notice the face-like visage unless pointed out.

On the other hand, the "bee orchids" actually are an example where it seems that the flowers have evolved in a way that specifically mimics the appearance of bees (and wasps). These flowers mostly attract male bees and wasps who confuse them for lovely lady bees and wasps and try to mate with the flowers. In the process, they pick up a pollen sac / pollinia, and if all goes well they end up pollinating the flower (or move on to pollinate another one).