In broad terms, yes - the status quo that eventually stablized after the assassination of Lumumba was more in favor of the US than it was for the Soviets.

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To understand the goals of foreign powers in the Congo after its independence, we have to look at a fair bit of history.

The Belgians had vested economic interests in the Congo, and were by all accounts rushed out of the colony - they had originally intended for a decades-long process of decolonization, but, as tended to be the case with these patronizing plans for independence in the indefinite future, the colonizers' plans were upset by local unrest. The Évolué upper class of Congolese - those that had been westernized - began agitating for political freedom in the mid-'50s, and the looming decolonization of the surrounding countries put the Belgian Congo in a precarious decision, and, after serious riots in early 1959, the Belgian government suddenly decided to fast-track independence. Congo would be free not in several decades, but several months. The problem here was that the Congo was massively unprepared for self-rule. Fewer than 10 Congolese had a college education at the time of independence, and the apparatus of the state, military, and economy was largely staffed by Belgians, as there had been no effort to train locals for these roles. For Belgium, the intention here was obvious - a nominally independent Congo would still be largely controlled by Belgian nationals, particularly in the mining sector, where Belgium had derived much of the wealth of the colony in recent years.

Patrice Lumumba and the MNC party he led upended these plans. Unlike Kasavubu's ABAKO or Tshombe's CONAKAT, MNC worked to appeal to the Congolese population as a whole rather than a particular local national group. MNC won the 1960 elections and Lumumba ended up as the head of the government. Lumumba had made it clear that the Congo was to be truly independent of Belgium in no uncertain terms and became a tremendously popular figurehead.

The clash between the Congolese people and Belgian neocolonial efforts began on independence day. A Force Publique officer - a Belgian national - agitated his Congolese troops by insisting nothing had changed in terms of command and in doing so he sparked a mutiny. This mutiny soon spread through the country, and, instead of calling in Belgian soldiers to put down the mutiny, Lumumba dismissed the Belgian officers entirely. Lumumba worked to pacify the soldiers and was successful with units closer to the capital, but in much of the country, the mutinying soldiers exacted vengeance on the colonizers by targeting Belgian nationals and Belgian-owned property. A Congolese government divided between a more pro-Belgian Kasavubu and independent Lumumba did begrudgingly agree to Belgium sending in some troops, but by then it was too late.

Less than two weeks after independence, Moise Tshombe's CONAKAT declared the secession of Katanga province - where the valuable mining interests were located. From the start, the Belgians were clearly behind the move - they immediately threw their support behind Katanga, and Belgian nationals were quickly placed into the same high-level positions they had hoped to hold in the Congo as a whole.

Lumumba, with a paralyzed army in the midst of rebellion, turned to the UN for support. The UN was initially helpful - a resolution was quickly passed that called for the withdrawal of all Belgian troops and their replacement with a multinational peacekeeping force. Unfortunately for Lumumba, while the peacekeepers soon came, he found that their directives were infuriatingly narrow - they were not to help suppress the rebel Katanga and South Kasai provinces (the latter had seceded a month after Katanga under similar circumstances), and the Congolese Army was making little headway against the Belgian-backed rebels. He turned to the United States for support, but President Eisenhower refused to provide unilateral support.

So, after having exhausted all other avenues, Lumumba made the fateful decision that led to his assassination. He turned to the Soviet Union for support. Unlike the prevaricating Western powers or the neutral UN, the Soviets were happy to oblige. They began sending in advisors and materiel, and the Congolese Army began making headway in South Kasai.

The sudden involvement of the Soviets finally sparked the interest of the Eisenhower Administration in the conflict that they had been trying to stay out of. With Domino Theory fresh in everyone's minds, the Congo was particularly worrying to the US. Its rich natural resources included the very Uranium mines that fed the Manhattan project, and keeping the largest country in Africa out of Soviet hands suddenly became a top priority.

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The assassination of Lumumba that materialized was complex, and it reflected the complex politics of the Congo at the time. The internal struggle between Kasavubu and Lumumba gave the US leverage in Leopoldville, while Tshombe in Katanga was also keeping in touch with Kasavubu as his situation worsened. To make a long story short, a soft coup was performed and Lumumba's government was dissolved at the order of Kasavubu. An army colonel, by the name of Mobutu then stepped in and declared a coup, ostensibly to stabilize the situation, but, when Lumumba tried to flee to Stanleyville - an MNC stronghold, he was arrested. Soon after, was flown to Elizabethville in Katanga, beaten and tortured, and then murdered and buried in an unmarked grave.

[This post is getting long, so I'll continue with the aftermath in a reply to this]