You have really answered your own question and are obviously a bright girl.
You can divide men into two groups. Those that think the anus is for one purpose only and any interest signals a homosexual. Then there are those that actually enjoy the sensation of having something inserted gently into their anus. I do not know the percentages but I have heard that some 40% of men are interested in this sort of thing either receiving or giving. It has absolutely nothing to do with homosexuality so no worries there.
Some men, leading on from anal play, enjoy having enemas. They like the feeling of the rubber tube in their anus and the flow of warm water in their colon. They also like the feeling of cramp that will occur when full and the fading away of the discomfort when they relax. In these men, an enema will prompt an erection and if the tube is gently stroked in and out a little bit, an orgasm can result. This orgasm is in the anal canal and not caused by the prostate. As far as the prostate is concerned, it can lead to an orgasm if it is massaged by the proper device.
Women, too can enjoy the same procedures but without a prostate their pleasure can come from their G Spot which is located as a small area inside the vagina and to the front and which can be stimulated through the rectum. They can also enjoy anal orgasms via enemas or other means.
There are many web sites that answer questions on the sexual sensitivity of the anus but there are also opinions and information given by people who have done no research and have just jumped to conclusions as to the statistics of the subject. My impression is that there are no reliable figures on who likes what as the subject has been taboo for so long and medical researchers have tended to turn their backs on such matters for fear of being unprofessional. It is quite clear, however, that doctors recognise that pleasant sensations can be experienced during anal/rectal examination and that is why, if they digitally examine the prostate, anus or rectum, they make sure that they do it very roughly in order to ensure as much pain as possible. The same applies to vaginal examinations. It is hard to understand this brand of cruelty as body massage is supposed to be pleasant and relaxing so why cannot a medical examination in the anus, rectum or vagina be allowed to cause a fleeting moment of pleasure in some recipients while the doctor carries out his/her professional duty.
I once asked a doctor his opinion on colonic irrigation and he said that people have colonics because they enjoy them. He then said with a shrug that there was nothing wrong with this if it is enjoyed, then enjoy it.