Any cat that does not have a pedigree is considered a domestic longhair (DLH), domestic medium hair (DMH) or domestic shorthair (DSH). Like Heidi said, your kitty would be a DSH. He is probably a mix of many breeds and it is nearly impossible to tell what he might have in him.
His coloring and markings is brown tabby. There are several varieties of tabby...striped, spotted, ticked, classic, etc. Your other 3 cats with tabby markings look like classic tabbies. Classic tabbies have wide bands of color that look like they are swirled together.