Apple Pencil gen. 1 does not fit the lightening connector of my iPad 9th generation

As described, you perhaps have an iPad10 - and not an iPad9.

Here is Apple’s definitive compatibility list for Apple Pencil and iPad:

Apple Pencil compatibility - Apple Support

The first generation Apple Pencil uses the physical Lightning port of the Pencil and host iPad for both pairing and charging.

With the sole exception of the new iPad10, requiring a special adapter to connect the Pencil to the iPad’s USB-C port, the first generation Apple Pencil can only be used with compatible iPad models that have a Lightning connector.

New first generation Pencils now ship with this special adapter in the box along with the Pencil. However, some older stock purchased from retailers may lack the USB-C to Lightning adapter - and may instead have an older Lightning to Lightning Adapter.

For owners of older first generation Pencils, or for “old stock” new Pencils, the new special adapter can be purchased directly from Apple as an accessory.

https://store.apple.com/uk/product/MQLU3ZM/A

If you go to settings, general, about you should see the generation of your iPad. Also if you look into your iPad charging port if their is a piece in the middle of it that looks like a wall you do not have an iPad 9.

Check the rear of your iPad. Or go to Settings > General > About > Model Number and if you don’t see a number in the form AXXXX tap that row until you do. Find the model number there. Does it begin with “A260…”?

If not, yours is not a ninth generation iPad. Tell us what that model number is.