Sacrifice of Kain and Hevel: Is the road to hell paved with good intentions?

 I also thought it a blatant injustice that the one who pioneered and first conceived of the notion of sacrificing, should be relegated to such a dismal fate. There's a famous - and unresolved - debate in the Talmud if our daily prayers are meant to parallel the temple service or the prayers originated by our forefathers, Avraham, Yitzchak and Yaakov. Yet, well before these forefathers, it would seem that the first party who made a foray into the world of divine service was Kain. The biblical narrative makes no mention of Adam and Eve turning to God, beseeching Him, requesting anything on their own initiative. And yet, Kain, who literally gave all of humanity this most important institution of worship, receives little acclaim, but rather, ignominy and disdain. 

If anything, it was Hevel who copied Kain. Who wasn't an originator, or someone who paved a new way. Yet, Hevel comes out on top. His blood cries out, but certainly he's deemed more righteous. Kain is the callous one, Hevel, the one who truly understood what Hashem sought for the betterment of his world. As everyone knows, Kain becomes an itinerant wanderer; in some ways, he receives divine protection, the promise that no one will avenge Hevel's murder, but at the same time, his life seems one of misery. 

And perhaps even more surprisingly, we see God reach out to Kain, giving him an ultimatum, which Kain summarily ignores. Hashem gave Kain a choice, Kain speaks to Hevel thereafter, the biblical text making no mention of what he said, and then Kain strikes Hevel, killing him. Nowhere do we see that Kain knew that he'd be killing Hevel; no murder had theretofore been perpetrated. God also says to Kain, "When is your brother, Hevel?" echoing the question God directed to Adam, "Where are you?" meaning that presumably here, Kain had buried Hevel, explaining why his "bloods," Kain's and those of the children he would never have, were calling out "from the ground."

I always wondered why Hashem never complimented or commended Kain on his bold step of seeking a deeper relationship. If anything, there is something very profound in what Kain gave the world, yet it's something that receives little attention, or regard. Hashem's ultimatum seems very sterile, dispassionate almost:

“Why are you distressed, And why is your face fallen? Surely, if you do right, There is uplift. But if you do not do right Sin couches at the door; Its urge is toward you, Yet you can be its master.” https://www.sefaria.org.il/Genesis.4.6-7?lang=en&aliyot=0

Frankly, I don't have answers. I always thought that Kain got the raw end of the deal, a bad rap, one wholly undeserved. There are a few like vignettes in the Torah that have always confused me. God is supposed to be the most masterful of teachers, he knows Kain's proclivities and limitations, God speaks to him, resultantly, he speaks to Hevel, and boom, Hevel's dead. The lacuna is startling...what in the world did he say? Far be it from me to sound deterministic, but if Hashem isn't going to fill in the missing detail, what are we supposed to think about the exchange, how can we learn to better ourselves. In fact, the Rambam says ever so beautifully that if you have a grievance, speak to the person who grieved you so that s/he doesn't repeat his errant deed. The Rambam's interpretation on Vayikra 19:17 is so simple: don't harbor hate in your heart, speak to the offender - otherwise you'll cause him to err again. 

And so, what should Kain have done differently? I would ask the same question about Sarah after she laughed on learning that she'd be with child. Hashem questions, "Why did she laugh?" What should Sarah, our mother, have done differently?