Batting first, Namibia could only manage a modest 196/9 in their alotted 50 overs.
Jacks and Brook then produced a 130-run partnership to help England overhaul the target in just 24.1 overs.
Jacks remained unbeaten on 73 runs, with 12 boundaries an a six studding his 44-ball innings. Brook was not out on 59, hitting 12 boundaries over the course of his 48-ball stint in the middle.
The Namibia batsmen did reasonably well against the strong England bowling.
Their openers Jurgen Linde and Lohan Louwrens gave them a steady start before solid knocks from Sam Fouche, Petrus Burger and Nicol Loftie-Eaton helped overcome stagnation in the middle order.
But Namibia's inability to capitalise on a reasonable start proved costly in the end.
Leg-spinner Luke Hollman was the most successful among the England bowlers with figures of 3/41 in his 10 overs. Brook and Tom Scriven bagged two wickets each.
England had a steady start to their chase with their openers Savin Perera and Tom Banton scoring 55 runs between off eight overs.
Fast bowler Gerhard Lottering rekindled Namibian hopes with two wickets in back to back overs.
Banton was the first to go when he a delivery onto his stumps. Perera was dismissed in Lottering's next over when he mistimed a pull and was caught at square leg.
Brook and Jacks then came together to produced some attacking batting and carry England to victory.
The duo found the boundary in almost every over while the Namibia bowlers did not exactly help their team's cause by giving away 19 runs as extras.
Brief scores:
Namibia: 196/9 in 50 overs (Shaun Fouche 44, Nicol Loftie-Eaton 36; Luke Hollman 3/41, Tom Scriven 2/30, Harry Brook 2/32) vs England: 198/2 in 24.1 overs (Will Jacks 73 not out, Harry Brook 59 not out; Gerhard Lottering 2/33).
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
