What is meant by the beginnings in the Gospels?

The sending of the Word of God, announced in the Old Testament

Isaiah 55

6 Seek you the LORD while he may be found, call you upon him while he is near:

7 Let the wicked forsake his way, and the unrighteous man his thoughts:
and let him return unto the LORD, and he will have mercy upon him;
and to our God, for he will abundantly pardon.

8 For my thoughts are not your thoughts, neither are your ways my ways, says the LORD.

9 For as the heavens are higher than the earth, so are my ways higher than your ways,
and my thoughts than your thoughts.

10 For as the rain comes down, and the snow from heaven, and returns not there, but waters the earth,
and makes it bring forth and bud, that it may give seed to the sower, and bread to the eater:

11 So shall my word be that goes forth out of my mouth:
it shall not return unto me void, but it shall accomplish that which I please,
and it shall prosper in the thing for which I sent it.

Gospel of Matthew

Matthew 4

17 From that time Jesus began2 to preach, and to say, Repent: for the kingdom of heaven is at hand.

2 Greek: ἄρχομαι (archomai): to begin  Beginning of the Word Proclamation of the Good News

Gospel of Mark

Mark 1

1 The beginning of the gospel of Jesus Christ, the Son of God;

Gospel of Luke

Luke 1

1 Since many have taken in hand to set forth in order a declaration of those things
which are most surely believed among us,

2 Even as they delivered them unto us, who from the beginning were eyewitnesses, and ministers of the word;

Luke 3 M315

23 When He began His ministry, Jesus Himself was about thirty years of age,
being, as was supposed, the son of Joseph, the son of Eli,

Gospel of John

John 1

1 In the beginning was the Word, and the Word was with God, and God was the Word.

2 The same was in the beginning with God.

3 All were made by him; and without him was not anyone made who was made.3

4 In him was life; and the life was the light of men.

5 And the light shines in darkness; and the darkness overcame it not.

3 The new creation concerns first people, not things!

As in the other gospels, it is also about the beginning of the proclamation of the Word of God
to the people through the man Jesus Christ, the Son of God.

Through Him God speaks today. (Heb. 1:2)

The Lord Jesus Himself testified that the words He speaks are not His, but of the Father who sent Him!

Jn 3:34; 5:38; 7:16; 12:49, 50; 14:24; 17:8.

So also here it is not about the first days of creation, but about the new creation.
Confirmed also by 1 Joh 1,1 from the same writer:

1 John 1 (NAS)

1 What was from the beginning, what we have heard, what we have seen with our eyes,
what we have looked at and touched with our hands, concerning the Word of Life

2 and the life was manifested, and we have seen and testify and proclaim to you the eternal life,
which was with the Father and was manifested to us –

3 what we have seen and heard we proclaim to you also, so that you too may have fellowship with us;
and indeed our fellowship is with the Father, and with His Son Jesus Christ.

God creates new people, people from above, through His Word, by means of His Son.
(are you also one of them?):

2 Corinthians 5 M315

17 Therefore if any man be in Christ, he is a new creature: the old has passed away;
behold, all have become new.

Galatians 6:15; Revelation 1:8; 21:6; 22:13