Starting with a program in memory would require that program to have been in ROM and then loaded into RAM on boot, but space in ROM was at a premium back in those days. However machines of that era did the next best thing, they provided some of the best computer manuals ever which focused on the use of BASIC and had plenty of examples for people to type in and play with.
Also the magazines back then had listings that you could type in (and usually then debug). They even had columns where you could write in with your problems and one of their "Experts" would provide some help or advice in a future issue. Yes you did have to wait a couple of months to see your answer in print, but seeing other people's solutions to other people's problems really helped.