How did the first people to climb Everest do it without modern technology we use today?

Mount Everest was not the first mountain to be climbed. Humans had summited plenty of mountains before Everest that prepared them to climb Everest and allowed them to learn lessons that would be needed to climb Everest. Mount Everest was the highest summit but not the first.

Oxygen at very high altitudes is needed. This was recognized before the first ascent was made. Everest was actually attempted once before, in 1922. The climbers who attempted this mission knew the importance of supplemental oxygen and brought with them oxygen equipment they had previously used to climb Mount Everest. This was done despite all of the extra gear and weight they had to bring.

Climbers in 1953 were experienced and well trained. Many of the team of two British climbers who made it to the top were experienced mountain climbers who had previously climbed Mount Everest and K2. The fact that they already knew from personal experience what was needed aided them in their quest.

Climbers were willing to go to great lengths and were willing to die to climb Everest. Even with all of the modern gear we have today, climbers to not always make it to the top of Everest. They still face avalanches, ice, weather, and other dangers.

There were very few people who even attempted to climb Mount Everest. It is now more commonplace to do so than it was in 1953. Even today, there are still not all that many people who have actually stood at the top of Mount Everest.