Did some people only have names like 张三? Some novels seem to say that in village life (or within a hutong) poorer children often had no personal given name.  Some characters in realistic seeming novels are known only by family name and birth order and have no other name.  But I have only seen this in novels and I wonder if it really happened.

In Europe even into the 20th century some people had no family name but were known only as say "Nathan's son John" where Nathan was literally the father and not a family name.  On the other hand, in places where childhood mortality was high, many children would not be named until they reached a safe age of 10 or 12 years.  Such a child might be called "The oldest Jones girl" or "the middle Jones boy" but I do not think it was ever so organized as "Jones one, Jones two...."

Many good sources discuss highly developed Chinese customs of having personal names and public names, and changing these over a lifetime, in well-off families. I have not found good historical sources for naming practices among farmers or the poor.  

Were some people in the past actually known just by names like 张三?
Were some people in the past actually known just by names like 张三?

Yes. It is the official name of some people, not just one. Some female even names as 张三妹. Bu the way 刘三姐 is a very famous movie.

张三, 李四, etc. are not nicknames, they are real names, they are also used as a "any one" placeholder, as in the answer of other question. For example, 你到那儿去，认识谁是张三，谁是李四啊. Going to that far, you do not know whom to contact.

Add more: (How are those names now?)

My father has a very close relative who is 李四 officially. He would be 80 or 90 now. 

On my mom side, there are two brothers having names 大水, 二水. The man 大水 was born the year of a huge flood. It is smart to use 大 for big/huge and also for the first son. In Chinese 老大 means the eldest son. 

Ha, you will see, 老大 is the head of an criminal gang. Haha, again, you understand the joke, Xi DaDa. 

By the way, check out sons of 赵紫阳, from 赵大军 to 赵五军, (at least five).