Little girls are experts at detecting adult creepiness. An adult might not think another adult is creepy, whereas a little girl will detect that right away and be repulsed.
If you don't want a little girl to think you are creepy, you need to be real. That means acting naturally, not putting on a fake persona. The creepiest thing is when an adult modifies their personality to play up to a girl's perceived sensitivities. Girls can tell when you are being fake.
The only ones you should worry about thinking you are creepy are the little girls themselves. Adults have too much going on to care all that much. If you are convenient for them, then they don't care if you are odd or not, as long as they are benefitting in some way by associating with you. The most they care about is that you are polite and 'nice' to them.