I think it's fair to say most people would agree that a truth is something you saw with your own eyes.
Example: I pick up an object. I go to a window. I open the window. I hold the object out of the window. I let go of the object. It falls to the ground.
Anybody anywhere can perform the same experiment and observe the same result.
This is an example of science in its simplest form. Science is all about observation. Except that science also goes on to ask "why does it fall?"
I think the majority of people would not be going for a walk on a 25-story, 4 inch ledge, expecting to fly.
There are some things that are truths from human experience.
Example: If you drop a hammer on your foot, it will hurt.
This is an example out of past experience, and general knowledge of being alive. I don't expect it's necessary for most people to have to perform this experiment themselves to validate its truth.
I have travelled to about 30 countries. As far north as Inverness. As far south as the Straits of Magellan.
I have observed a few things with my own eyes.
1. The sun doesn't set in the far north in the summertime. You can walk out of a bar in Inverness at 11.30pm and it will still be light.
2. There are dinner-plate-sized tarantulas in the Amazon. I saw one.
3. The glaciers are receding. I have seen Grey Glacier in Patagonia with my own eyes. It's hundreds of feet further back than it used to be.
4. Sea levels are rising. I have seen markers in places that show where ocean levels were, and where ocean levels are now. Global Warming is real.
There are levels of evidence.
1. First level evidence - one's own observation
2. Second level evidence - The observation of a close and trusted friend
3. Third level evidence - The obervation of a trusted third party - possibly a news reporter with actual video, or a trusted friend of a trusted friend
4. Fourth level evidence - General observations by unverified miscellaneous sources e.g. the internet
What happens if you can't go and see something with your own eyes? You go to level 2 next. Then level 3. Level 4 is a last resort.
Example Level 2: Someone I have travelled with before went to India. I have never been to India. She showed me photographs of her trip. I believe she went there, and saw what she saw. She takes beautiful photos, by the way. It really documents life in the towns she visited.
Example level 2: Someone I know has a friend who died of Covid-19. Covid-19 is real.
Example level 3: A reporter on local news photographed Covid-19 patients connected to ventilators in a local hospital . I know that hospital. I don't have to go and visit it personally to understand that Covid-19 is real and dangerous.
I was in the medical field for 25 years. I have personally seen the effects of multiple viruses, and am old enough to remember the days before vaccines for common childhood diseases were routinely available. Example: MMR (Measles, Mumps, Rubella) was first introduced in the early 1970s. I had already had all three of those as a child before the vaccine was available.
What did we do when a Measles outbreak was running rampant round the schools ? Kids stayed home.
I'm not going to discuss Level 4. People have many sources they believe are "trusted". I would say Trust but Verify. Verify 10 times. Verify 100 times. No one source is the only source, and posting links to sources must be verified from a level 1 - 3 source.
Of course, no-one has to believe me. I'm just a random source on the internet that you don't know. Verify. Verify 10 times. Verify 100 times. But verify with someone level 2 - 3. Better yet, get off the keyboard and go and see the evidence with your own eyes.