You say that as if giving credit is enough. If you don't have a license/permission to use the image you're violating copyright and the correct response is to take it down.
Several of them might fall within the bounds of fair-use, such as the one about halfway down showing the debris trail, which is included in the context of a discussion of the debris trail. The large image at the top isn't used in a way that would make for a good fair-use argument, though.
They all fall under fair use since they were uploaded to social media (so the photographer is no longer the only rights holder and most social media sites assign rights to republish content).
That said, it is only fair and nice to credit all sources. The web relies on links and being able to source content back to origins.
Design is about choices. In this case you can point out:
1. top-left square logo, dark gray, slab serif, fixed on scroll
3. bold, large sans-serif title in "off-black"
4. large serif body text with extended line-height
5. 100% width image on top
Despite the visual simplicity, there are a lot of variables in effect. It's definitely "inspired" by Medium.
I think that the lack of author information in the top left is sufficiently different to not even call it gray area. And the lack of paragraph-level comments.
The logo and typography seem very similar, even to my untrained eye, though.