Is this a majority opinion among people that study this sort of thing, or is it your own informed position? Which I am not trying to discount by the way. You are extremely well learned brother.
In Rig Veda Rudra already had many aspects of Siva (the auspicious one). He had braided hair, when happy he brought healing and prosperity to all, but when angry, could destroy anyone with his unbridled power.
Rig Veda 1.111
1. These poetic thoughts do we proffer to Rudra,
the powerful one with
braided hair who rules over heroes,
so that he will be luck for our two-footed and four-footed, so that
everything in this settlement will be flourishing, free of affliction.
2. Be merciful to us, Rudra, and create joy for us. To you who rule over
heroes we would do honor with reverence.
Whatever luck and lifetime Father Manu won through sacrif i ce, that may
we attain under your guidance, Rudra.
3. May we attain your benevolence though sacrif i ce to the gods, the
benevolence of you who rule over heroes, o reward-granting Rudra.
Bestowing only favor, come roaming toward our clans: possessing heroes
who cannot be harmed, we will pour you an oblation.
4. We call down
turbulent Rudra for help, the wandering poet who brings
the sacrif i ce to success.
In
the distance from us let him shoot his divine anger. It is just his
benevolence we choose.
5. We call down with reverence the
boar of heaven, flame-red, with
braided hair, turbulent in form.
Bearing in his hand
desirable healing remedies, he will extend shelter,
covering, and protection to us.
6. This speech here is spoken to the
father of the Maruts—speech sweeter
than sweet, strengthening to Rudra.
Both grant us, immortal one, what nourishes mortals, and be merciful
to our selves, to our progeny and posterity.
7. Not the great one among us nor the wee little one, not the growing one
among us nor the grown—
don’t smite our father nor our mother. Don’t harm our own dear
bodies, Rudra.
8. Don’t do harm to our progeny and posterity nor to our (own) lifespan,
not to our cows nor to our horses.
Don’t smite our heroes, Rudra, when enraged. We, with our oblations,
will always invoke you.
9. Like a cowherd, I have driven these praises close to you. Grant your
favor to us, father of the Maruts,
for your benevolence is auspicious(Siva) , most merciful. It is just your aid
that we choose.
10. In the
distance be your cow-smiting and men-smiting (anger). You who
rule over heroes, let your favor be on us.
Both be merciful to us and speak on our behalf, o god, and then extend
double-lofty shelter to us.
11. We have spoken reverence to him, seeking his aid. Let Rudra,
accompanied by the Maruts, hear our call.
– This let Mitra and Varuṇa grant to us, and Aditi, River, and Earth
and Heaven.
He is also symbolized as a bull.
Rig Veda 2.33
7. Where, o Rudra, is that
merciful hand of yours, which is a healing
remedy,
the bearer away of malady that comes from the gods? You should now
be indulgent toward me, o bull.
8. To the
red-brown, bright-faced bull, I rouse forth greatly a great good
praise hymn.
I shall do reverence to the sparkling one with acts of reverence. We sing
the turbulent name of Rudra.
9. With sturdy limbs, the mighty red-brown one of many forms has
adorned himself with gleaming golden (ornaments).
From Rudra, who is master over the abundant living world, lordly
power will surely not be distant.
10.
Worthily you bear the arrows and the bow and worthily the sacrificial
neck ornament of all forms.
Worthily you parcel out the whole formless void. Surely there exists
nothing more powerful than you, Rudra.
11. Praise the famed youth, sitting upon the high seat, the mighty one,
pouncing like a terrifying wild beast.
Being praised, have mercy on the singer, Rudra. Let your weapons cast
down another than us.
12. Even a little boy bows in response to his approving father as he
approaches, o Rudra.
I will hymn the giver of much, the master of settlements. Praised,
bestow on us your remedies.
13. Your gleaming remedies, o bullish Maruts, which bring best luck, which
are joy itself,
which our father Manu chose—those of Rudra’s do I want as luck and
lifetime.
14.
Might Rudra’s lance avoid us. The hostile thought of the turbulent one,
though great, shall go around us.
Slacken the taut (bows) for our bounteous (patrons). Be merciful to our
progeny and posterity, o munificent one.
15. You red-brown bull, constantly visible—(let it be) so, that you do not
become angry, o god, and you do not smite.
Hearing our calls, be aware of us here, Rudra. – May we speak loftily at
the ritual distribution, in possession of good heroes.
