Tears of the Kingdom is very much a sequel, so I dunno if I can recommend it as your first Zelda game from a lore perspective, but that said, I am a firm believer that the best game for anyone to start with in any series is whichever one grasps your interest first. There might be games that are objectively better introductions to the series than Tears, but if this is the first one to pique your interest when the others never did I don't think that's something to be ignored. My two cents.
If you want to know which one I think gives the best introduction to the series, I'd say any of Ocarina of Time, A Link to the Past, Wind Waker, Twilight Princess, or Breath of the Wild are great choices.
My personal favourite Zelda game is Majora's Mask, but like Tears, it suffers from too much of being a sequel to Ocarina of Time for it to be a person's ideal "first game," and it also is a big enough departure from others in the series in terms of its gameplay to make it a poor introduction for the rest of the series in general.
I think that for this game specifically, it is better to play Breath of the Wild first. Perhaps that is because of my own experience with the games, but I really felt like this game was "Let's see how everything changed" and Breath of the Wild was really the introduction into the world.
I think Breath of the Wild is a fine starting point, but I think it's important to know that it's not very representative of the "Zelda style." I started with Wind Waker and loved it, but I do feel like most Zelda games are fine starting points.
I'd recommend it as much as any other Zelda as a starting point. While it markets itself as a sequel to Breath of the Wild, it's as much a sequel to that game as lunch is a sequel to breakfast. It does its best to contradict and outright ignore most of BotW, so you won't miss out on much by jumping in here.
Depends, but otherwise I say absolutely. It feels a bit like a retelling of many events of BotW, which is why a lot of people are still arguing about it. However, if you don't care too much about the shallow plot, the game is a BLAST. I introduced it to my friend who hasn't touched a single LoZ game since ALTTP came out & he's been delighted & says he's into LoZ again for the first time in many years. It's these games that really hooked him specifically because he doesn't know much & the gameplay itself greatly encourages experimentation with any skill level. They're both fine starts in my opinion, & TotK in particular has a ton of quality of life improvements to BotW, which already was a very strong game to play (not counting plot, which is mixed).
As a starting game, I would reccomend BotW over TotK. That's seeing as TotK is a sequel first and foremost. But if you're going to play BotW for the sake of getting to TotK, just play the latter. Since they are very similar and exist within the same world, playing them back to back is probably not the best idea. So if you wanna play BotW now and get to Tears later that's cool, but if you can't wait just skip to the second one. The story isn't totally dependant on the first.