Welcome to the forum!
They're called "homecasts", because they were made with molds that were sold to hobbyists, to cast their own figures at home. The first generation of molds came from Germany in the 1890s, and were made of bronze. Soon there was a second generation of molds made here, starting with copies of German molds, but also including new designs. Two of the most popular makers were Junior Caster and Home Foundry. Also, Gilbert, Co, the maker of Erector Sets, produced a line of molds, and there were numerous smaller makers.
Most homecasts aren't really worth much more than their melt value, unless you have a figure from a mold that is relatively rare. It's difficult to pin the age of a casting down, because many of the molds still exist, some have been reproduced/reissued, and you can make a casting using tire weights, and it'll look like something that was buried in the backyard in 1910. Value will also depend on the detail of the casting, which is influenced by the quality of the mold and alloy used. A crisply engraved mold, and a white metal alloy, can give a crisply detailed casting. A poor quality mold, with a soft alloy, will tend to have soft detail.
The cyclists in the top photo are from German molds, made by the company Schneider Bros. in Leipzig, who made their molds from the 1890's until the end of WWII. Their molds were reissued, though, by two makers in West Germany, from about the 60s up through the 90s and the Reunification.
Most of the castings in your pictures, though, aren't really that clean, and in my opinion, they're really only worth the value of the metal for melting down and using for new castings.
If you can, look for Richard O'Brien's "Collecting Toy Soldiers", for more specific info about homecasting. That's where I have most of the info I've posted here.
Prost!
Brad
