I don't think a TV show would've been such a hit. There's something about the shared experience of cinema that works really well for this film. I do agree that some of the characters were under-served, though.

I don't think that a "musical" TV show is necessarily doomed to failure. Glee ran for years, Crazy Ex-Girlfriend got 4 and even Galavant got 2 (and there have been a few others I haven't watched in recent years). The latter 2 featured 2 or 3 original songs in most episodes. In Galavant's case this was particularly impressive as it was a half-hour slot and the songs were from Howard Ashman and Glenn Slater. Actually, Slater has a Barnum connection in his CV. Hmmmm...

You are probably right, a TV show wouldn't have attracted all that much attention. Still, it would have been fascinating if they'd either stuck with actual Barnum life-facts or just left it as a feel good show. I haven't actually watched the shows you've mentioned. Good to know musicals aren't just movies though.

@Lightberry said:

Still, it would have been fascinating if they'd either stuck with actual Barnum life-facts

I think that the film was wise not to stick to facts as Barnum seems to have been a pretty horrible person in real life.

Off the shows I mentioned, Glee started well, but toned down when it got popular. The songs were cover versions initially sung in context of it being a Glee Club, but they soon started belting them out on a whim. Similarly Nashville (6th and final season running) and Smash (2 seasons) used their settings to provide an excuse for the songs. I've only seen one song from the former (C&W not my thing) and haven't had time to watch the latter, so I'm not sure if all the songs were justified by the setting or whether they just burst into song from time to time.

Crazy Ex-Girlfriend is a musical dramedy with mainly pop/rock "style" songs, but the characters to launch into song without needing a reason. Most of the songs are humorous, NSFW and pastiche various styles/songs/people. The trailer doesn't really sell it as it features one of the worst songs. Here's the only slightly unsuitable "Group Hang": https://www.youtube.com/watch?v=elrDmZxtLtU .

Galavant is well worth checking out. If you're in the UK, even though it was filmed there and the cast is predominately British, that's not going to be easy - the soundtrack is on Spotify, though. Imagine a cross between Monty Python and The Princess Bride with songs by Oscar winner Alan Menken (The Little Mermaid) and Tony nominee Glenn Slater (Tangled) with a lot of the songs reminiscent of famous musicals: Dwarves vs Giants (West Side Story), He Was There (Oliver), Today We Rise (Les Miserables). If What Am I Feeling? was in a show and not springing from what it was springing from, there wouldn't be a dry eye in the house https://open.spotify.com/track/6YgXqUF12QTXiuCsTj2UEu?si=jCwqAjW6T32ghV2wfCQ7hw (YouTube video spoils a great gag). Only 18 22 minute eps, so you could binge it in a weekend (or day!) and, while it was cancelled, the ending is perfect. Here's I don't Like You: https://www.youtube.com/watch?v=w-c6IFBByeI