SPOILER WARNING: If you haven't booted up Destiny 2 and would like to remain relatively unspoiled, then turn away now as this covers literally the first few screens you see before making a character.
Destiny 2 may get rid of all players' loot from the jump, but it doesn't want you to forget the original game. At the start, a series of sentimental memories roll; pleasant illustrations of big moments you shared in the original Destiny, whether it was beating the base campaign or taking on a raid. It's not just an illustration though. It also shows you the date you beat it, and who you took on the challenge with.
Then it dives into the character select screen, and you're face to face with your old hero—should you choose to continue the game with them. (I didn't, since I wanted to be a Warlock for a change.)
My preroll art reminded me of the time I beat the game on accident with a friend, where our conversation was distracting to the lengthy endgame cinematics themselves. For other players, the memories are either nice or the opposite. On Reddit some players noted that they are being reminded of their exes that they used to play with, semi-souring their memories on the first game. For another, a player found it heartwarming to unexpectedly see a friend that recently passed away immortalized in the game from the time they shared together.
Destiny 2 for some veteran players is a hard pill to swallow, erasing all their hard work from the prior game. Some players are even turning their backs on the game because of it. Nonetheless, the Destiny 1 art slideshow is a kind way for Bungie to show players that their experiences with the game were not for naught. If anything, they solidified memories (both good and bad), and they'll always be remembered in some shape or form, even if you don't have any shiny new loot or exotic weapons now to show for it.