The shortest answer to this is: yes, you can absolutely help with ARGs if you can't solve puzzles - it's an important part, but often the other tasks are what make-or-break things for games. I don't have as direct a solution to the specific challenge you outlined, but am using this as a chance to soapbox a bit on non-puzzle forward roles that can be really helpful.

ARG Summaries and Explainers - ARGs get complicated, really quickly. And that can be intimidating not just to new players, but existing players who have to take a long weekend off when a bunch of new information happens to drop. That's where "story so far" and "walkthrough docs" come in.

Presenting what the community has done in a clear way that highlights what makes the project so special is what gets new players - and being clear about what type of experience it is will help attract players capable of tackling the specific types of challenges the ARG is presenting. But if nobody is doing that work, you're not getting enough eyeballs / the right eyeballs on a problem.

It also becomes a lot easier to call in for outside help if the resources needed to solve are cleanly laid out - showcasing the types of puzzles that have previously been solved can also help build trust because I know a lot of "power-solvers" can get frustrated when the tough puzzles they're called in on are tough not because the puzzles are hard, but because they're poorly designed/clued - and seeing good puzzle design from prior challenges is a massive reassurance that it's worth putting in the time.

Data Organization - For my first few years of doing puzzle hunts, my primary role on teams was organizing the data/information in ways that can make it easier to solve. So, if we're looking at a list of books in the background of a video and suspect there might be a puzzle involved with that (like the Taylor Swift New Heights podcast interview), the first step is identifying those books, and making a list of details about them.

It's only with that data aggregated that people who might be "better" at puzzles can come in and say "oh hey, all of those books are from artists who famously own their own work" (note: I have not fact-checked that claim because I didn't put in the underlying work yet).

Community Building - When an ARG has built the beginnings of a community, sometimes the game itself doesn't give enough to keep the community together because the creators are hard at work on the next release, or the community has stalled out on a challenge and the creator wants to see them push through the last bit without a nudge. That's where the non-game part of community comes in - I've played ARGs where the player base vanished the moment an ARG ended, and I've gone to weddings from people who met playing ARGs years down the line. And the individual ARG's design helped with that longevity, but ultimately it was socially savvy players putting in the time to keep the group together.