Is there not in the scriptures that there is a “mighty cloud of witnesses” ?
Yup, contextually referring to those examples of faith who went to Heaven, but which does not even hint that such are to be objects of prayer to Heaven. And if any book would teach that, it would bve Hebrews. Instead it clearly tells believers to look to Jesus, who is the only Heavenly intercessor btwn man and God, and is uniquely qualified to be so:
"Wherefore seeing we also are compassed about with so great a cloud of witnesses, let us lay aside every weight, and the sin which doth so easily beset us, and let us run with patience the race that is set before us," "Looking unto Jesus the author and finisher of our faith; who for the joy that was set before him endured the cross, despising the shame, and is set down at the right hand of the throne of God." (Hebrews 12:1-2)
"Seeing then that we have a great high priest, that is passed into the heavens, Jesus the Son of God, let us hold fast our profession." "For we have not an high priest which cannot be touched with the feeling of our infirmities; but was in all points tempted like as we are, yet without sin." "Let us therefore come boldly unto the throne of grace, that we may obtain mercy, and find grace to help in time of need." (Hebrews 4:14-16)
"Having therefore, brethren, boldness to enter into the holiest by the blood of Jesus," "By a new and living way, which he hath consecrated for us, through the veil, that is to say, his flesh;" (Hebrews 10:19-20)
"Wherefore he is able also to save them to the uttermost that come unto God by him, seeing he ever liveth to make intercession for them." (Hebrews 7:25)
"For there is one God, and one mediator between God and men, the man Christ Jesus;" (1 Timothy 2:5)