That seems rather naive.
He was a well educated individual of some status, that had traveled a great distance to acquire a scroll of
the Prophet Isaiah. (at great expense) And driving a chariot. (like someone driving a Corvette today)
Knew nothing? Get real.
With all due respect sir did you read the story as God had it recorded I ill post it for your viewing
Acts 8:
26 And the angel of the Lord spake unto Philip, saying, Arise, and go toward the south unto the way that goeth down from Jerusalem unto Gaza, which is desert.
27 And he arose and went: and, behold, a man of Ethiopia, an eunuch of great authority under Candace queen of the Ethiopians, who had the charge of all her treasure, and had come to Jerusalem for to worship,
28 Was returning, and sitting in his chariot read Esaias the prophet.
29 Then the Spirit said unto Philip, Go near, and join thyself to this chariot.
30 And Philip ran thither to him, and heard him read the prophet Esaias, and said, Understandest thou what thou readest?
31 And he said, How can I, except some man should guide me? And he desired Philip that he would come up and sit with him.
32 The place of the scripture which he read was this, He was led as a sheep to the slaughter; and like a lamb dumb before his shearer, so opened he not his mouth:
33 In his humiliation his judgment was taken away: and who shall declare his generation? for his life is taken from the earth.
34 And the eunuch answered Philip, and said, I pray thee, of whom speaketh the prophet this? of himself, or of some other man?
35 Then Philip opened his mouth, and began at the same scripture, and preached unto him Jesus.
36 And as they went on their way, they came unto a certain water: and the eunuch said, See, here is water; what doth hinder me to be baptized?
37 And Philip said, If thou believest with all thine heart, thou mayest. And he answered and said, I believe that Jesus Christ is the Son of God.
38 And he commanded the chariot to stand still: and they went down both into the water, both Philip and the eunuch; and he baptized him.
39 And when they were come up out of the water, the Spirit of the Lord caught away Philip, that the eunuch saw him no more: and he went on his way rejoicing.
read it carefully not as to miss what is said
The spirit sent Philip ot this poor soul who was reading he prophet Esaias and Philip asked if he undestood what he was reading and He answered How can I, except some man should guide me? So Philip began at the same scripture, and preached unto him Jesus.
And as they went on their way, they came unto a certain water: and the eunuch said, See, here is water; what doth hinder me to be baptized?
Now it said nothing about Philip preaching baptism but apparently he did while preaching Jesus (The gospel of Christ) otherwise why would the unlearned eunuch asked to be baptized in water must have heard it in the gospel of Christ you think? I bet is was the same one Peter preached on the day of Pentecost when he opened the doors to the church and God started adding to the church those responding this way to the gospel call.
Same gospel from Peter given him by the spirit from God same one Philip preached as well as Paul and all of Gods spokesmen until this day.
Biblical proof that to preach Jesus (the gospel) is to preach the baptism in the name of Jesus Christ Acts 2:38
Hope this answers your question and thanks for hearing me out May we always speak the oracles of God and keep searching the scripture for in them are the words of truth and eternal life.