Anyone feel like an imposter going back to school

I know this sounds silly but I walked into my first class last week and literally everyone looked like they were twelve. I sat way in the back the whole time just convinced I didn't belong there at all. Maybe someone else feels this way too because I'm really wondering if that nervous feeling ever goes away or if I just have to push through it anyway. I'd love to hear how other people got past feeling too old to actually do this thing, because right now I'm not sure I can keep showing up when I feel this out of place.