When did commericials start featuring recurring characters and overarching storylines.

To me, the best example of this is James Garner and Mariette Hartley in the Polaroid commercials. I don’t recall an overarching story line, but it was clear that each commercial is a brief peak into the life of this couple.

Flo and her family camping out. The actress plays all the characters. Then her sister buys a house. There’s the family at a holiday dinner around the table. Progressive has really put alot eggs in this basket. Hope it holds up for them.

Back in the '50s, when television shows were sponsored by a single company, it was common to see the show’s characters doing commercials. You could see Andy and Opie and Aunt Bee sitting down for breakfast with Sanka coffee. Ozzie and Harriet carried this to ridiculous extremes, folding product placements into their show’s episodes, so Coca Cola and Kodak cameras drifted seamlessly from show to ad and back to show, always in the hands of the stars.

Radio did the same thing, in some cases, with a neighbor character who would just show up, comment on the episode’s storyline, segue into a description of the virtues of Johnson’s Glowcoat, and wander off.

Viewers believed with such a certainty that they were an actual couple that when Ms Hartley got pregnant, she took to wearing a shirt that said “This is not James Garner’s baby!”

Upon reflection, I agree. Plus there is water at the bottom of the ocean.

The original Energizer Bunny commercials started out with the bunny on the set of a commercial and continuing to move after the director called “cut!” Then the bunny started intruding into other ads, as if he was moving from one set to another. So there was at least an “origin story” of some sort, even if subsequent ads didn’t really have much of a storyline.

I hate Flo and her whole family. My God! What have I done?

Ancient Chinese Secret!

Ouch.
All their faux hamming it up, um, really really grated.
Buddy with smiley Burger King mask making creepy appearances was the greatest recurring commercial character of all time. The Greatest.
I can get behind Captain Obvious.

If we’re using that critera, one of the earliest was the Old Home Bread campaign of 1974, which featured a bread truck driver and waitress gradually falling in love. Here’s the full campaign.

Mikey.

(with four or five follow-up ads over the years)

These aren’t all that old, but the Japanese company Sakeru made a series of commercials about their products that is known today as “Long Long Man”. It tells a complete story right to the last commercial (and stick around for the end). Collection can be found here: Sakeru Gum series さけるグミ #1-11 complete (Eng SUB) - YouTube with English subtitles.

Not sure if this is what you’re looking for but how about the Subaru dog family? We’ve seen them drop one of the “kids” off for the first day of school, go to a carwash, go out to eat, teach the teenager how to drive, go to the park where pets aren’t allowed, road trips, and probably more that I don’t remember right now.

I love those commercials. I’ll rewind so I can watch it again!