Much how certain technologies adapt in such a way that only a generation or two in and people can't imagine life before these things we now take for granted I surmise that future technologies will come in a similar fashion. Once we marveled at the fridge, the microwave, the toaster, washers, dryers, dish washers, air conditioning, computers, lasers, light bulbs, and so much more yet just a century ago a majority of these things either didn't exist or were extremely new. Just as phones and cars have become indispensable I have seen some potentials that would more than rival such inventions. Among them is organic metals and something I can't entirely describe but the closest existing thing would have to be electro magnets. Organic metals would do more than create the first cyborgs, organic computers and man machine interfaces they would revolutionize the creation and maintenance of all known kinds of materials. It would change so much in so many ways and literally be everywhere to the point that considering a time before it would be tantamount to blasphemy. Imagine everything you use, touch, sit on, work with, and much more all made from the exact same material yet it's so versatile you'd almost never guess. A small electrical current provided by your body bends it to your every will turning it into a vehicle, a couch, a stove, a fork, a writing utensil, or nearly anything else you can imagine and it is self cleaning and repairing making it so you have no maintenance to worry about ever. This isn't some utopian fantasy it's a tech I've seen first hand and it's one potential future we may have under the right conditions.
Then there's this object relation tech which is as best I can describe it. It produces a field similar to a magnetic field and it can be manipulated to alter object relationships creating attraction and repulsion in complex forms, such as limited attraction and repulsion or in strange directions. It apparently changes inherit properties of objects passing through its field and can do some uniquely interesting things. I've seen it extract iron from rock without damaging the rock at all, and then reshape the iron into bars and balls without heat or melting. I've also seen it remove cancer which was quite remarkable, as well as making vehicles levitate, and so much more. This tech could be applied to just about anything and seem like a miracle, though I imagine it could easily be a weapon which is why it should be held back until it won't be needed as one.
The interesting part from what I've seen really isn't how much the world changes, or how much it doesn't change, it's how alien everything ends up seeming. throughout the majority of the past that includes humans things are relatively similar among most timelines. As I move further out though the more different things become.
For today's time traveling advice I highly advise not eating food prior the 1920's and preferably as little as you can in foreign timelines. Some of it will kill you as expected but almost all of it will make you sick. This is because things are radically different in terms of the kinds of bacteria that exist in that time and health standards etc, not to mention flora and fauna or the dozens of other factors involved. And if you're going back to the early days of humanity or back further I recommend an environmental suit from the future preferably one that's heavily armored. The centipedes that exist in the age of dinosaurs are the size of anacondas and they are vicious. Not to mention the oxygen content is so much higher it makes it hard to breathe properly.