The list is pretty long and I'm not sure they would be the builders of all the megaliths around the globe.
https://en.wikipedia.org/wiki/List_of_Mesopotamian_deities
The oldest God is the one in Ge:1:1. This is His son's version of 'the past'.
Proverb:8:22-36:
The LORD possessed me in the beginning of his way,
before his works of old.
I was set up from everlasting,
from the beginning,
or ever the earth was.
When there were no depths,
I was brought forth;
when there were no fountains abounding with water.
Before the mountains were settled,
before the hills was I brought forth:
While as yet he had not made the earth,
nor the fields,
nor the highest part of the dust of the world.
When he prepared the heavens,
I was there:
when he set a compass upon the face of the depth:
When he established the clouds above:
when he strengthened the fountains of the deep:
When he gave to the sea his decree,
that the waters should not pass his commandment:
when he appointed the foundations of the earth:
Then I was by him,
as one brought up with him:
and I was daily his delight,
rejoicing always before him;
Rejoicing in the habitable part of his earth;
and my delights were with the sons of men.
Now therefore hearken unto me,
O ye children:
for blessed are they that keep my ways.
Hear instruction,
and be wise,
and refuse it not.
Blessed is the man that heareth me,
watching daily at my gates,
waiting at the posts of my doors.
For whoso findeth me findeth life,
and shall obtain favour of the LORD.
But he that sinneth against me wrongeth his own soul:
all they that hate me love death.
Angels have seen how the universe was created, that makes them about 40B years old as that is when matter began to clump together, Adam saw the garden starting 400,000BC. Mankind is destined to gain the same knowledge.