The first generation iPad cannot be updated beyond iOS 5.1.1. The iPad1, a 32-bit device, is long ago obsolete.
You need to consider that compatible Apps for your iPad are not available - as developers have dropped all support for 32-bit devices and most for iOS versions preceding iOS11/12/13. As older versions of Apps are removed/retired from the Apple App Store, you’ll not be able to (re)download or install them - which may severely limit the usefulness and utility of your iPad.
As such, if you want or need to access current Apps, requiring more recent versions of iOS than your iPad is capable of support, you have no alternative other than to consider replacement of your iPad with a much newer or current model.
Of current models, even the cheapest entry-level iPad9 has specifications and capabilities that will massively outperform you current iPad - and is compatible with the vast majority of current Apps. Other models are more powerful still.
I hope this information provides succinct clarity as to your available options - and the fundamental limitations of your iPad1.