According to this review article, adults need a bit more than 1 gram of calcium per day. However, it may be the case that the natural vitamin D levels for the human body should be a lot higher than what is currently the norm, see e.g. here. Calcium is absorbed from the gut by both passive and active mechanisms, the active mechanism is vitamin D dependent. If the level of calcium in the blood drops then calcium from bones will be released and simultaneously, the kidneys will produce more calcitriol which then turns on genes in the gut to produce enzymes that help to extract calcium from food.
Besides the total intake per day, what is also relevant is the presence of big gaps in the intake of calcium. Such gaps will prompt the body to extract calcium from the bones and then you're dependent on processes that will eventually put calcium back into the bones. By spreading the intake of calcium over the day, you can prevent bone loss in the event that in your case this mechanism of putting the calcium back doesn't work as well as it should.
Note that there are many sources of calcium that we tend to ignore. Water can contain calcium, e.g. where I live there is 60 mg per liter. That doesn't sound like a lot, but if you drink 3 liters a day, you'll get 180 mg. Bread only contains 10 mg per slice, but if you eat a lot like I do (I don't recommend doing that unless it fits into a well balanced diet for your case) like 15 slices per day, then that's 150 mg of calcium. So, the dry bread plus water alone is already 280 mg.
Then if you eat 500 grams of broccoli at dinner like I did today, you'll get 235 mg of calcium. Potatoes contain 12 mg per 100 gram, I had 1 kg of potatoes for dinner, so I got 120 mg from the potatoes. This means that in total I got more than 600 mg of calcium from sources one normally doesn't bother to consider. However, it must be said that absorption of calcium from such sources isn't as efficient as from dairy products due to oxalates in vegetables, phytic acids in grains and the lack of phosphorous when you drink just plain water.
So, you see that non dairy sources can give you a decent amount of calcium, but you then need to eat a lot (I eat about 4000 kcal per day, which is a lot more than average). The calorie intake of indigenous people who needed to jog for hours every day to chase prey was likely a lot higher than what it is today for the typical office worker, so they may actually have gotten their gram of calcium per day from only non dairy foods and their vitamin D levels were also likely a lot higher than that of the average office worker.