Your scientists were so preoccupied with whether or not they could that they didn't stop to think if they should.
The 21st century was the dawn of humanity's advancement. Technology had expanded at rapid pace, benefiting humanity's future, especially those who were living in developing third-world nations across the globe. Diseases thought to be incurable were able to be cured, and species were saved from the brink of extinction caused by human encroachment upon their natural habits. The 21st century seemed like a nice era to live in, and it only continued to be better century to live in as the years went on.
Seemed.
Whilst the 21st century was a century of technological marvel, it was also one of political turmoil. Countries found themselves at odds over nuclear technology and terrorism, rocking the political climate of the globe. With nations bickering over tariffs and economic issues, some conspiracy theorists considered the chance of another world war taking place, and in the end, the conspiracies they had established would prove to be partly true.
The United States, despite having the strongest military power on Earth, were sure that tensions with countries like Russia and China would break out into open warfare. They knew they had an edge over their political rivals, yet the United States wanted more. Project JX-04132, otherwise known as Project Nimbus, was a military project aimed at controlling teleportation for the American military. Would it had been successful, the United States would've been able to teleport entire armies and fleets to different fronts.
Despite their attempts at harnessing godly powers, the United States were unable to control what they created. Unbeknownst to the scientists working on Project Nimbus, a small error in their calculations opened a connection to an ancient timeline hosting an prehistoric Earth. Time rifts appeared throughout the planet, sending nations into panic as dinosaurs and other primordial creatures walked through the portals confused and hungry. Society as it was known began to collapse, and the world population begun to plummet until it was barely a blimp on the radar.
Now, after several decades, the 22nd century is rolling around the corner. Earth has been ravaged by dangerous beasts, and humanity still struggles on to regain its place at the top of the food chain with mini settlements scattered throughout the globe. However, you aren't some important settlement figure, such as the leader or a doctor. You are a youth trying to live how a kid should live, having fun with your childhood and getting into mischief despite knowing nothing of the world that came before.
The only issue is that with mischief comes trouble–five and half to eight metric tons of trouble.