A new open-source editor and engine, called Pyrite64, has just been released, making it easier than ever for people to design and create their own 3D N64 games. This means we could theoretically be seeing an influx of new original games for the system in the future.
As stated in the FAQ, the engine still requires knowledge of C++/C, so you'll need to have some programming background. It also doesn't allow you to mod existing N64 games or export games to PC. But what it does do, essentially, is set out to streamline the process of creating original 3D games for the 64-bit Nintendo system, providing users with modern tools and pipelines to make the process a little less confusing.
Some of its stated features, for instance, include the ability to import 3D models from Blender that have been built using the fast64 plugin, code object behaviour with C++ scripts, manage assets, and script sequence of events with a Node-Graph editor. There's also support for rendering larger textures (256x256), as well as implementing HDR+Bloom, and a built-in runtime engine "handling scene-management, rendering, collision, audio, and more."
The engine is the creation of Max Bebök (HailToDodongo), and is available under MIT license, meaning you should be able to sell any games you make without issues. It reportedly does not use any proprietary N64 SDKs or libraries, but was instead built using libdragon and tiny3D, which are available under similar licenses.
As Bebök states, he recommends using Ares (v147 or newer) and gopher64 if you decide to play your creations in an emulator, stating projects built in Pyrite64 require "accurate" emulation to function.
A demo project, Cathode Quest 64, is also available in the GitHub repo, giving you an idea of what's possible with the toolset.
Here's the link to the project's GitHub page.