- There are superhuman abilities all over the place! Lots of common folk can do things like see in the dark or cast simple cantrips, or even higher-level spells like hellish rebuke, even before you start discussing class levels.
- Death is reversible. In 5th edition, a 5th level cleric can revivify a corpse if they’ve died within the last minute. This very much looks like tech medical researchers are perfecting even now. Many common folk have natural lifespans measured in centuries.
- Enhanced reality and magical make-up! Lots of normal folk can toss around cantrips like thaumaturgy before you even start talking about class levels. High elves have access to the entire wizard list of cantrips, and these include things like lesser illusion, mage hand, and mending. A single 3rd level cleric can light every street-corner in town (given enough time) with continual flame.
- Mind hacking is a thing. While friends and charm aren’t the spells they used to be, crown of madness and dominate person allow you to adjust a person’s behavior in real time, while suggestion, geas, and modify memory can distort or even reshape a personality.
And keep in mind, everything I’ve discussed above is available to characters below 10th level of ability. Modify memory and geas are 5th level spells, available to 9th-level wizards. I haven’t gotten into the really reality-bending stuff like teleportation circles, control weather, earthquake, true polymorph, or wish.
However, as in cyberpunk, the future is unevenly distributed. High elves are the big winners, having universal access to wizard cantrips and the longest life spans. Poor humans are at the bottom of the stack, though they do appear to have improved facility towards learning and personal development.
Just how uneven the distribution is depends on your campaign. 5e doesn’t assume, the way 3e did, what sort of campaign you’re running. If you decide that most priests can’t even manage a cantrip, then even kings might not have access to revivify. However, in most campaigns I’ve seen, almost every village has someone capable of casting at least lesser restoration, meaning they’ve got a 3rd level cleric or druid around. The rules for the teleportation circle spell state that “[m]any major temples, guilds, and other important places have permanent teleportation circles inscribed somewhere within their confines.” The DMG walks this back a bit, but there’s a strong implication that 9th-level wizards and sorcerers are thick enough on the ground to make these things useful to commercial and religious institutions (who usually don’t create wizards as part of their regular activities). Keep in mind, it takes a year of casting and over 18k gp (assuming a 365-day year) to create just one circle AND you need a 9th-level wizard or sorcerer at the other end, where people will be teleporting from. This isn’t the sort of thing you’re likely to do on a whim.
So while your standard D&D campaign may lack the usual trappings of a transhumanist setting, it has a lot of the mechanical parts of one. This should make transhumanist lit a good source for mining plots, conflicts, and themes for your D&D game.