No, winmore is the card only does something when your winning and when your neutral or behind, it's generally bad. Narset's actively good in a neutral board by virtue of being a PW since they generally give you a cards worth of value every turn. When you're behind, it depends on how much time/mana you have wether narsets still good or bad. She's generally gonna be bad when behind against aggressive decks and slow, but good against more midrangey and control decks. If you're opponents on a siege rhino strat for example, if they have just a rhino in play, you're actually fine playing narset since you're 50/50 or better to hit off it and if they don't have the downfall or another rhino, narset does good work to catch you back up since most abzan midrange decks win by snowballing CA in board advantage and narset can buy back CA to neutralize board advantage slowly but inevitably. If it's a deck with rabblemaster and seeker in play, then you have to use other cards before playing narset most likely unless your life totals high enough where you can gamble and/or don't have the requisite cards in hand to fight back. Even then, you have the chance to lucksack into value scenarios.
But how is that different in a way that is better than, say, Outpost Siege or Chandra +0? The former, they cannot attack it. The latter ... is probably a bad example because that 1 damage isn't particularly impressive vs. gaining loyalty and having the card to keep as needed (though this seems less the case in your sample deck vs. an archtypal UW control deck).
How does "coin toss" draw a card "catch you up" on board vs a Rhino, aside from the obvious "draw into a
wrath valorous stance" scenarios?
In a deck like jeskai, narsets actually good against both aggressive and Controlling decks since jeskai has a ton of cheap burn to trade with the 2 drops letting you pull ahead later. I have no idea why you think this card is bad. You're saying words and making statements that make sense, but only from a flawed perspective. It's like you want every card to be jace the mindsculptor and do all the things all the time. All your examples generally ignore sequencing or over simply game states.
How am I providing a flawed perspective when the words you're saying to me are "Narset is good against decks you claim it is bad against because other cards in my deck that aren't Narset are good against cards in those decks"? That sounds like cards in your deck are well positioned against cards in Heroic, and Narset has no impact on that. That doesn't mean Narset is bad. It just sounds like it does absolutely nothing on its own to win the matchup beyond +1ing into a Lightning Strike, meaning it doesn't sound particularly great in that specific matchup. Which is fine, that's not what I'm saying about Narset or saying it needs to be. And as far as I can tell, that's not what Narset is or is supposed to be.
I won't respond to the strawman of my comments.
3 tokens is also a lot more then 6. 3 tokens and a jeskai ascendancy get stonewalled by an Elspeth. 6 tokens and the same kill an Elspeth dead.
Unless your tokens have haste, you get 6 tokens over 2 turns, Elspeth makes 6 tokens over 2 turns, and you're at a stall that Elspeth eventually wins because she keeps making tokens barring outside interference from additional cards.
A wrath resets a board against x-creature deck, but if they paced there cards, they rebuild next turn. A rebounded wrath is a pseudo timewalk if they don't have haste creatures or PWs to play into. In fact a rebounded wrath is actually a perilous vault affect only you don't have to pay life equal to whatever power they have in play to get the timewalk out of them which is absurd.
One thing you definitively get over the x-creature deck is that coin-toss for drawing a card, which is a definitive boon in that scenario and gives the Wrath + Rebound experience legs. It should be noted that neither you nor your opponent get to put creatures into play effectively and you're both drawing a card and gaining a land drop/playing non-creatures (which the Narset side of the board is favored with because of her ultimate, -2, and ability to draw more of than the other player).