They aren't like any of the 200 or so Playpeople klickies (Marx toys, UK licensee) I have, none of which has unmarked feet. So, perhaps some other licensee? Eleven licensees produced fixed-wrist klickies (based on set box pictures in Collector); Antex, Kenbrite, Trol, Lyra, Japan, Irwin, Korea, Aurimat, Famobil, Marx and Schaper. They could be one of those or knock-offs!
I have Trol, Lyra and Famobil fixed-wrist klickies, all of which have lettering with a ridge around the edge of the sole, but the ones you have are perhaps earlier examples before lettering was used.