DO NOT use the charging/pairing adapter that came in the box with your 1st gen Apple Pencil.
That adapter maybe the older Apple Lightning to Lightning adapter that is still used with older iPad models that still use Apple's Lightning port.
You need to have purchased and be using the older, original 1st gen Apple Pencil with an additional purchase of Apple's new $9 U.S.D. USB-C to Lightning adapter.
USB-C to Apple Pencil Adapter - Apple
You may have purchased an older “new” stock box 1st gen Apple Pencil that still contains the original Lightning to Lightning adapter, inside of the box.
This is the wrong adapter to be using with the new base model 10th gen iPad.
This is why Apple is selling this new, proper $9 U.S.D. USB-C to Lightning adapter.
New stock boxes of 1st gen Apple Pencils are, supposedly, being reported as shipping with this newer USB-C to Lightnng Apple Pencil charging/pairing adapter, presently, but old “new” stock boxes of 1st gen Apple Pencils are still packaged with the older Lightning to Lightning Apple Pencil charging/pairing adapter.
That older adapter will NOT work with the new base model 10th gen iPad with a USB-C port.
If you purchased the actual $9 USB-C to Lightning adapter, to pair and charge your 1st gen Pencil to the iPad, your charge cable needs to be connected by plugging in your iPad's USB-C to USB-C charging cable into the iPad and plug the USB-C end of the Adapter into the loose/free USB-C end of the cable and then plug the Apple Pencil into the Lightning end of the adapter.
To charge the 1st gen Pencil away from the iPad, plug your charging cable into the Apple power/charging block, take the other loose/free end of the USB-C cable, plug that USB-C end of the adapter into the loose end of your USB-C charged cable and then plug your 1st gen Pencil into the Lightning end of this adapter.
The sooner you purchase this $9 USB-C to Lightning adapter, the sooner you can start charging, pairing, and using your 1st gen Apple Pencil with your new 10th gen Apple Pencil.
Best of Luck to You!