Long ago, at many times and in many ways, God spoke to our fathers by the prophets, but in these last days he has spoken to us by his Son, whom he appointed the heir of all things, through whom also he created the world. (Hebrews 1:1-2 ESV)
The prophets were a long distance messenger service. God chose and tasked them with delivering his messages to the people of Israel verbatim. I imagine that it must have been challenging for them to authenticate anything that a prophet said unless their words were accompanied by some kind of sign or miracle. They served as secondary sources of communication, making it easy for anyone to remain skeptical.
Here, the writer of Hebrews just cuts to the chase and tells us that Jesus is the primary source because he is God himself. He spoke to his disciples and continues to speak to us because his words were recorded in scripture. Jesus said, “Heaven and earth will pass away, but my words will not pass away,” because they are also written on our hearts, the heirs of eternal life (Matthew 24:35; Jeremiah 31:33).
“For this is the covenant that I will make with the house of Israel after those days, declares the Lord: I will put my law within them, and I will write it on their hearts. And I will be their God, and they shall be my people.” (Jeremiah 31:33)
To further build your faith, also consider what Jesus says to Philip:
Philip said to him, “Lord, show us the Father, and it is enough for us.” Jesus said to him, “Have I been with you so long, and you still do not know me, Philip? Whoever has seen me has seen the Father. How can you say, ‘Show us the Father’? Do you not believe that I am in the Father and the Father is in me? The words that I say to you I do not speak on my own authority, but the Father who dwells in me does his works. (John 14:8-10)