You know very little. Collective human knowledge is much larger.
There are people much better than you who believe they don’t know everything. Listen to Elon Musk once and you’ll know.
There may even be kids much better than you are.
Everything you see around you was made by group of humans working together. Many sacrificed themselves to their work to make these things a reality.
You live in a country where you have basic facilities: Internet, House, Food, Water. Hopefully you have a family and a few good friends. There are many who aren’t as lucky who live in a poor 3rd world country and or war zones.
Universe has been here for billions of years and will be around for billions. Like every one human being, you’ll die one day. What you leave behind is your knowledge and your work.