Thanks for the background explanations. I was curious about why I couldn't install the Gospel Library app on my iPad 1. I did come up with some potential workarounds, though, none of them are as convenient as having the Gospel Library app, but they might be helpful to someone.
1. I found out that the Deseret Bookshelf app, which is available for the iPad 1, does have the Scriptures (and a few other excellent Gospel books) for free. For the Scriptures, this seems like a great option. Of course, it doesn't really give you easy access to other LDS materials (at least with the little time that I spent with the app). It does provide methods for adding notes, highlights, and bookmarks to books and can sync them across devices--all very handy. Additionally, the footnotes are included in the Scriptures and hyperlinks (or just "links") in the footnotes can take you directly to the references.
2. Using lds.org in the Safari browser isn't a bad option for getting to the Scriptures and other LDS materials, but, of course, it requires an Internet connection and it doesn't seem to provide a convenient way to do annotations or bookmarks (beyond what the browser already does). There are some annotation and bookmarking features when viewing the Scriptures using desktop web browsers, but I don't seem to see those features when using Safari on the iPad 1.
3. Downloading the various books from lds.org in PDF or .mobi formats using Safari and then opening the documents with either the Adobe Reader app or the Amazon Kindle app isn't a bad way to go. The Adobe Reader and Amazon Kindle apps provide methods for navigating the documents (not as good as other options) and making annotations. The PDF versions of the Scriptures have the footnotes where I didn't see them in the .mobi versions of the scriptures. The .mobi version of the Scriptures does seem easier to navigate.
I know this doesn't really solve the problem of getting the Gospel Library app onto an iPad 1, but it might help someone.