Is it generally accepted that these wavelengths and devices that operate them are safe around humans? Should I feel concerned at all having so many large antennas and amplifiers and what not near me?
I never really stopped to ask this of my phone either, I guess.
Generally accepted by who? You can find some people who are concerned about this stuff. 5G truthers and all that. But nobody in the evidence-based medicine community.
Nothing is entirely free from risks. That's part of why we do studies on things like this. But, for example, the second study on the page you linked concludes: "At the present state of knowledge there is no positive evidence that pulsed or continuous microwave exposure in the non-thermal range confers elevated risk to the health of the brain."
The mere presence of studies on a subject does not indicate positive evidence of material risk to health.
This section of the EM spectrum is non-ionizing. So unlike, say, X-rays, you won't get cancer as the waves aren't strong enough to strip an electron off an atom and therefore change your DNA. However, they will heat your cells to some degree (since 2.5GHz is the same freq as a microwave). This can cause cataracts over long exposure to high enough power as your eyes can't regulate heat.
I never really stopped to ask this of my phone either, I guess.