I made it to S2 before I had High Khatun as well. Most of the way there I used Athel, Courtier, Warpriest and Spirithost. I don't know if Athel was 6* at the time or not, but the rest were definitely not on account of them still not being 6*. At some point I switched Warpriest for Shaman (also still 5*). Apart from Athel who had some 4* rare/epic stuff (lifesteal from the new player rewards), they were mostly equipped in 2-3* gear from the campaign. The team was without a doubt considerably worse than anything posted above. I think I was in S1 when I switched out Courtier for Madame Serris that I was lucky enough to get. I think my player power was around 200k or thereabout at the time.
So yes, you absolutely can get to silver as a new player, but in my case it was for the single reason that I didn't open any shards because I had been told to wait until 2x events (I opened 4 or 5, don't remember, void shards during the first 2x event I was in, which is when I got the aforementioned Serris). It wasn't until the 2x ancient shard event that my player power jumped up to about 300k and I could no longer maintain my arena position. It took about 10 minutes, or however long I spent opening shards, for the arena to go from reasonable to impossible. There are some posts when I documented this while trying to figure out the matchmaking system, and evidently I was correct.
This is not an argument that the arena is fine. It's in fact the complete opposite. Whether your position is that a team like I used shouldn't be able to get to S2, or that it should, it just serves as further evidence that the matchmaking is completely absurd. Either I shouldn't have been able to get as high as I did to begin with, or I should arguably be able to do so now when my team is considerably better. Neither is the case, and instead the game arbitrarily punishes the player... for playing the game. I'm not sure what possibility I find more concerning; that no one realized what this would do before they added it, or that they did and added it anyway. I have some theories on why they might've, but let's just say they are not very flattering.