To be clear, the first and second generation Pencil use entirely different charging and pairing interfaces. The two models of Pencil are not interchangeable.
A first generation Pencil is charged via a direct connection to the Pencil; pairing between iPad and Pencil is also performed over a direct Lightning connection of compatible models of iPad. By comparison, the second generation Pencil charges - and initiates pairing - via the proprietary inductive coupling of compatible models of the 2020 iPad Air and 2018/2020 models of iPad Pro.
The two models of Pencil are technically different products designed for entirely different system architectures. A technological analogy might be that of VHS and Betamax video. Both herald from the same era; both are designed to store and play video media - and perform the precisely the same function. However, both the recording tapes and transport mechanisms differ and are not interchangeable between players.
Returning to the Pencil, even if direct connection of a first generation Pencil to a USB-C port were feasible, the 2020 iPad Pro and Air models are not designed to pair with the Pencil over a USB interface.
Industry standard USB-C and Apple’s proprietary Lightning interfaces are entirely different - and without an active interface converter are not inter-workable. The USB-C Audio adapters are not interface converters - but instead contain an audio DAC that is needed to connect analogue headphones.
You appear to be at the crossroads of technology. Apple are, for flagship iPad models and Mac, moving towards the latest industry standard - this being USB-C - and away from proprietary data interfaces. iPhone and standard models of iPad continue to use the proprietary Apple Lightning interface.
Along with much of the consumer product industry, for mobile devices Apple are moving away from providing a direct 3.5mm audio connection in favour of wireless connections. This provides a number of engineering benefits, but also introduces “challenges” for those Users with a desire (or need) to use a wired audio connection.
Technology moves forward. As consumers, we have no alternative other than to move forward with it. We are all free to make choices as to the devices we buy and use - but sooner or later the [current] technologies that we use will be replaced with something new.
It is perhaps true to say that we will forever be in a state of “transition” - no matter whose product(s) we buy.