Not a single instance of baptism being reserved or restricted to adults can be found in Scripture, not one.
See how that works for both of us?
We have Scripture of Jesus with children,
Matt 18:13Then were there brought unto him little children, that he should put his hands on them, and pray: and the disciples rebuked them. 14But Jesus said, Suffer little children, and forbid them not, to come unto me: for of such is the kingdom of heaven. 15And he laid his hands on them, and departed thence.
What can we glean from that? That parents brought their children to Jesus. What are the ages of the children? One? Two? Three? Four? Five? Six? Seven? Eight? Nine? Ten? Eleven? Twelve?
Did they leave the infants home?
—Matthew 18:1-6, 10-14
At that time the disciples came to Jesus, saying, “Who is the greatest in the kingdom of heaven?” And calling to him a child, he put him in the midst of them and said, “Truly, I say to you, unless you turn and become like children, you will never enter the kingdom of heaven. Whoever humbles himself like this child is the greatest in the kingdom of heaven.
“Whoever receives one such child in my name receives me, but whoever causes one of these little ones who believe in me to sin, it would be better for him to have a great millstone fastened around his neck and to be drowned in the depth of the sea.
“See that you do not despise one of these little ones. For I tell you that in heaven their angels always see the face of my Father who is in heaven. What do you think? If a man has a hundred sheep, and one of them has gone astray, does he not leave the ninety-nine on the mountains and go in search of the one that went astray? And if he finds it, truly, I say to you, he rejoices over it more than over the ninety-nine that never went astray. So it is not the will of my Father who is in heaven that one of these little ones should perish.
And what do you make of this verse?
For behold, when the sound of your greeting came to my ears, the baby in my womb leaped for joy.
—Luke 1:44
What does Paul mean here?
Children, obey your parents in the Lord, for this is right. “Honor your father and mother” (this is the first commandment with a promise), “that it may go well with you and that you may live long in the land.”
—Ephesians 6:1-3
And with adults and so what does that have to do with infant/adult baptism?
“And what do you make of this verse?”
I would ask the question above, What does Luke 1:44 have to with baptism?
“What does Paul mean here?
Children, obey your parents in the Lord, for this is right. “Honor your father and mother” (this is the first commandment with a promise), “that it may go well with you and that you may live long in the land.”
—Ephesians 6:1-3”
I think he's instructing children to obey their parents. He was giving counsel in the fifth and sixth chapters to wives, husbands, children, slaves, masters and others unspecified.
All fine Scriptures to be sure.