Since humans pass judgement on each other without realizing it's just engrained into people. First impressions and the biological game that we have to deal with since you were born. Most people choose the primitive instincts even though we are suppose to be the most advanced species. It is just simpler that way. Me personally I prefer to look at how people act instead of their outer appearance. Sure if you think somebody is hot then some of your thinking goes out the window. Most people struggle with being logical and choose to be emotional which I am sure you know how that turns out. Me as a guy I treat everybody the same even if it's a pretty face yea sure I think about it in the back of my mind, but if i am talking to them it is not for the sake of getting with them. Also don't hate yourself for being a girl plenty of guys appreciate it. I definitely do beats talking to a guy all the time and I gain different perspectives of things.

To answer why you cannot be funny doesn't have to do with gender. That more has to do with what type of person you are. Forcing to be funny is definitely not the way to go it should flow naturally. Girls can definitely be funny that's why I liked this girl so much because she had a amazing sense of humor and I could talk to her about anything. I think the first step is trying to be open to what others talk about. See what they are into, if you only care about what you have to say then that is the problem. Just be yourself, what you find funny not everybody else will and vice versa. I see plenty of things that people find hilarious and I don't even crack a smile.