Good luck! I’d not worry about being funny or particularly interesting, when speaking at public events I generally just speak like I naturally would, it takes the pressure off. The other thing is that I like to laugh at myself. If my face gets red or I make a mistake presenting, i just laugh at myself. I try not to take myself too seriously, it takes ton of pressure off myself and others.
I have several colleagues who aren’t shy speaking in front of the kids and teens but are anxious speaking in front of the adults. If you aren’t worried about speaking in front of the kids, then maybe when speaking in front of adults pretend that they are kids.