This is why it can be tricky trying to predict the values of cards before a set is out in the wild, as you never know which cards will get pulled into relevance
It's just, as Steve said, different people want different things, and the nice thing about trading card games is we can make cards for different people because there are so many cards
Shiva's abilities develop until the end of turn three, when its owner has to sacrifice it
Ideally you'd be putting this on something withy lifelink to keep the gains going, or even Qala, Ajani's Pridemate to increase the buff when it swings with other creatures
A single marketplace isnt the whole market, but it sees enough volume to be a strong signal
With a darker twist in line with its title, it really does feel like Whispers in the Well is hinting at more for the game more in the sense of unique mechanics, theming and even artwork