In the Old Testament (OT) it is clear that the inspired Bible writers intended holy spirit to be understood as an invisible, powerful force from God. Even many trinitarian scholars will admit that.
For example, p. 269, The Catholic Encyclopedia, 1976, admits: “In the OT the Holy Spirit means a divine power ...”
And the New Bible Dictionary, Tyndale House Publishers, 1984, pp. 1136, 1137, says:
“Spirit, Holy Spirit. OT, Heb. ruah 378 times...; NT, Gk. pneuma 379 times.” And “Divine power, where ruah is used to describe...a supernatural force....” And “At its [the Old Testament’s concept of God’s spirit] heart is the experience of a mysterious, awesome power - the mighty invisible force of the wind, the mystery of vitality, the otherly power that transforms - all ruah, all manifestations of divine energy.” And “at this early stage [pre-Christian] of understanding, God’s ruah was thought of simply as a supernatural power (under God’s authority) exerting force in some direction.”
The Encyclopedia Americana tells us:
“The doctrine of the Holy Spirit [as a person who is God] is a distinctly Christian one.... the Spirit of Jehovah [in the OT] is the active divine principle in nature. .... But it is in the New Testament [NT] that we find the bases of the doctrine of the Spirit’s personality.” And “Yet the early Church did not forthwith attain to a complete doctrine; nor was it, in fact, until after the essential divinity of Jesus had received full ecclesiastical sanction [in 325 A.D. at the Council of Nicaea] that the personality of the Spirit was explicitly recognized, and the doctrine of the Trinity formulated.” Also, “It is better to regard the Spirit as the agency which, proceeding from the Father and the Son, dwells in the church as the witness and power of the life therein.” - v. 14, p. 326, 1957.
And Britannica agrees:
“The Hebrew word ruah (usually translated ‘spirit’) is often found in texts referring to the free and unhindered activity of God, .... There was, however, no explicit belief in a separate divine person in Biblical Judaism; in fact, the New Testament itself is not entirely clear in this regard....“The definition that the Holy Spirit was a distinct divine Person equal in substance to the Father and the Son and not subordinate to them came at the Council of Constantinople in AD 381....” - Encyclopedia Britannica Micropaedia, 1985, v. 6, p. 22.
Yes, not only did God’s people, as described in the OT, believe the holy spirit was an active force and not a person, but that same belief prevailed from the time of the NT writers up until at least 325 A. D. when the Roman Church officially accepted and began promoting the first stage in its new doctrine.
“In the N[ew] T[estament] there is no direct suggestion of a doctrine of the Trinity. The spirit is conceived as an IMPERSONAL POWER by which God effects his will through Christ.” - An Encyclopedia of Religion, Ferm (ed.), 1945, p. 344.
We should be aware that every important, oft-mentioned individual in both testaments has a personal name. God is YHWH (Jehovah/Yahweh/Yehowah); God's only-begotten Son is Yehoshua/Iesus; the Holy Spirit's personal name is ?????. That's right this extremely important 'person' is never given a personal name.
We also should be aware that both the NT Greek and the OT Hebrew are languages which assign genders to its nouns and pronouns.
Gender in both Old and New Testaments is given to mature individuals according to their sex. "Man" is masculine in both Testaments; "woman" is feminine; "God" is masculine; etc.
But, as we would expect, this "impersonal power" (the Holy Spirit) is given a gender in the Hebrew and Greek scriptures befitting its meaning as a non-person.
In the Greek "Holy Spirit" is neuter and so are the pronouns which are used for it.
There is no use of a neuter gender in Hebrew, but the feminine is often used in its stead. And yes Holy Spirit" is feminine in the Hebrew text. (Neuter in Greek and feminine in Hebrew!)