What, according to Jesus, is the primary purpose and objective of sending the Holy Spirit at Pentecost? After the Holy Spirit came at Pentecost and filled all those gathered together in that upper room in Jerusalem (Acts 1: 13-14), they were enabled to go forth and speak boldly about Jesus of Nazareth and how God raised him from the dead.  They spoke in tongues and performed miraculous healings (Acts chapter 2).
Is the primary objective of the Holy Spirit to imbue believers with the miraculous gifts of speaking in tongues, or of healing, or of prophecy?  Is the manifestation of those gifts of the Spirit in the believer proof that they are somehow superior to those who have never experienced such miraculous gifts?
What, according to Jesus, is the primary purpose and objective of sending the Holy Spirit at Pentecost?
EDIT for clarity: I'm looking for the words of Jesus, as found in the New Testament, which relate specifically to the purpose of sending the Holy Spirit at Pentecost.
The very words of Jesus on that matter are clear and are repeated below:

John 15:26-27: “When the Comforter is come, whom I will send unto you
from the Father, the Spirit of truth who proceeds from the Father, he
shall testify of me. And you also shall bear witness, because you have
been with me from the beginning”.
John 16:8-14: “And when he is come, he will reprove the world of sin,
and of righteousness, and of judgment; of sin, because they believe
not on me; of righteousness, because I go to my Father, and you see me
no more; of judgment, because the prince of this world is judged...
when he, the Spirit of truth is come, he will guide you into all the
truth, for he shall not speak of himself; but whatsoever he shall hear
shall he speak, and he will show you things to come.  He shall glory
me; for he shall receive of mine, and shall show it unto you.  All
things that the Father hath are mine.  Therefore said I, that he shall
take of mine, and shall show it unto you.”

The primary, foremost role of the Holy Spirit at Pentecost was NOT to imbue believers with miraculous gifts of a more spectacular nature than 'mundane' gifts of hospitality, administration etc., as if that would prove that those with spectacular gifts were somehow superior to those with 'mundane' gifts.  The words of Jesus show that the Holy Spirit does not speak of Himself - he points to, and glorifies, Christ.  Therefore, when the disciples at Pentecost found they could speak in other languages, they used that amazing gift to point thousands to the resurrected Christ. They preached Christ crucified and risen. They did not talk about themselves, but witnessed (testified to) having seen the resurrected Christ, and explaining how the prophecies about Messiah were fulfilled in Christ.
An illustration might be helpful. When thousands go to a sporting event in a huge outdoor stadium at night, and the flood-lights suddenly come on, does anybody turn around and admire the flood-lights?  Of course not!  The illumination is to enable them to see what is happening before their eyes.  So at Pentecost.  In that dark night of sin, when thousands gathered at Jerusalem to celebrate, the Holy Spirit suddenly flooded the city with the light of the gospel of Christ, so that all eyes were turned - not on the Holy Spirit - but on the disciples’ preaching, which was inspired by His power, for they could speak in other languages to reach those from other countries. They stood up and preached Christ crucified and risen in glory, and how the people could be delivered from their sin! They pointed to Christ, not to themselves or how wonderful their linguistic gifts were! All attention was drawn to the risen Christ.
Today, there are some who seem obsessed with having &quot;the spirit&quot;, including power of spiritual gifts. But if any such ones promote self as exhibiting &quot;the spirit&quot;, they cannot be denying self and pointing others to Christ. They have not learned the vital lesson of the Spirit bestowed at Pentecost - to work through saved believers to explain the gospel of Christ to others, so that those others might then be saved and experience the convicting power of the Holy Spirit, realising their sin and the need to repent and put all their faith in the risen Christ.