Have you had hail lately? The leaves in the second and third pics look like hail damage.

Maybe my eyes are bad, which is true to some extent :), but I don't see damage on your hosta in the photo.

The leaf in the second pic looks ripped off, like deer maybe, it's just such a tear unlike insect damage. That's why I suspected hail.

The pepper plant looks like it has a nip in it too. I hope someone with better knowledge than I have will come along. It's a bummer to see plant damage but they look healthy otherwise so hopefully will outgrow the tears/spots. Nature is pretty amazing and I applaud you for attempting to find out what is happening. It's all a science experiment and I understand the need to get some answers. Hope you have a really great growing season that exceeds your expectations.

I see damage like this in our yard, especially in the front garden that's in a public area. Petunias especially. The flowers look ripped off. But being an urban area with some crazy people, I can't rule out human damage. I hope it isn't. Heavy rain also tears leaves, I've noticed. Wind too. I hope someone can shed light on the cause here.