Etymology of "manhole"

I don't think man stands for male here, I think it stands for human—it is a humanhole. Does it have this name because its purpose is to provide access to the sewer for men?

The origin of “manhole” is indeed a simple combination of “man” and “hole”. “Hole” is easy enough to understand, but with “man” there's some confusion since the word nowadays refers to a specific gender.

In the OED, we find:

man, n.

I. A human being (irrespective of [gender] or age).
Man was considered until the 20th cent. to include women by implication, though referring primarily to [men]. It is now freq. understood to exclude women, and is therefore avoided by many people.
_{Source: “man, n.1.” OED Online. Oxford University Press, March 2014. Web. 14 April 2014.}

As is often the case with older senses of words, a sort of fossilization has occurred, whereby the older sense persists in certain compound words or phrases. In this particular instance, since the newer sense of that part of the word unneccessarily excludes approximately half of all people, some consider the word worth changing.

From MIT's Editorial Style Guide:

The American Heritage Dictionary of the English Language explains in a Usage Note that the word “man” has been used in the sense of the broader term “human” since Old English times. This, the Note goes on, results in “an asymmetric arrangement that many criticize as sexist.” Although levels of acceptance vary for each of the words in the left-hand column below (as well as for their feminine counterparts, of course), we offer some possible gender-neutral substitutions, should you choose to use them. Which we encourage.

[table omitted]
_{Source: Editorial Style Guide for The Office of Communications and Donor Relations, MIT}

For “manhole” they offer the alternatives “utility hole” and “sewer hole” which, judging by your question, you may find more accurate to the fact that these service hatches are not actually gender-specific.

Opponents of changing how we refer to “manholes” claim that such alterations to the language are “political correctness run amok” and point to lack of prior usage as evidence that nobody will understand anybody inventing new terms for these passages or their coverings. Indeed, despite increases in usage for various alternatives (which may not even be referring to the same item), the most popular term by far is still “manhole”. The choice is yours! I personally have no problem understanding when someone says “manholes” and likewise no problem being clear and terse while using other words for these things.

I'm not sure what OP means by "stands for" here - I'm pretty certain non-gender-specific use of the word man in English predates the very existence of the word human, so we can't really say it's a "short form".

Everything depends on context. If a product is described as man-made, or a commercial project is costed in man-years, this in no way excludes women from being involved. As it says here...

Some would argue that any use of the word 'man', e.g. manhole, is biased and should be avoided. Others are quite happy with female chairmen.

In short, this whole issue is nothing whatsoever to do with "meaning" as such. It just so happens it's an area of language usage that bothers some people for political/sociological reasons, not semantics.

It's not unknown for people to object to the word bitch, for example - simply because they've heard it applied to a woman in a derogatory sense more often than as a neutral reference to a female dog. Sometimes the very same people who argue for the man/woman distinction feel uncomfortable with the corresponding dog/bitch usage. I certainly never heard anyone suggest that a woman priest might wear a "bitch collar."