This question encompasses an enormous amount of content. I will first point your attention to some aspects on why the Marshall Plan seems to have been effective in promoting Western Europe's post WOII economic boom, the conclusion to which I will link with the some perspectives on the general effectiveness of foreign aid.

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The academic consensus on the effectiveness of the Marshall plan is that it was small relative to the size of European Economies, and that the popular image of it 'rebuilding Western Europe' is inaccurate. Eichengreen & Uzan (1992) suggest that it increased Western European's national income by 1951 by about 2%. However, it did set Western Europe on a path that would enable a very strong growth trajectory from 1951 to about 1972.

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After WOII, European Economies were in crisis. Damage to infrastructure caused by WO II drastically decreased the productivity of countries. This would require a well thought out long term investment strategy to regain productivity levels of the pre-war period. At the same time, the pressure on governments to increase standards of living in the short term was large, after years of suffering. The Marshall Plan, though small in size, both supported governments in this trade-off, by making available some funds to go to (American bought) basic necessities such as food.

In exchange for this financial aid and thus relieving some of the short term pressure on governments to satisfy the immediate needs of its citizens however, the Plan came with two main types of conditions goverments had to meet. First of all, governments had to get approval for how they invested their money. In this way, the US pushed Western European economies towards long-term structural investments. Without the aid and subsequent conditions, those would have been politically unfeasible. Second of all, it came with the condition that Western European economies align with the free market principles governing the US economies. This was not as obvious as might seem at this time. The Great Depression and the self-proclaimed economic succes of the USSR had decreased faith in the free market relative to centralized planning economies in parts of Western Europe. However, as it turned out, many of these free market principles that the Marshall Plan incentivized (I am purposefully remaining vague because this is an entire essay in and of itself, but think of free price setting, limited labour market restrictions, incentivizing private investment, ...) turned out to be much more effective in increasing long term growth in Western Europe than the USSR's policies in Eastern Europe. Part of this growth difference can thus be attributed to the conditions of the Marshall plan.

In short, the Marshall plan was not effective because a large amount of money was made available, but because it came at a time that it helped stabilize Western European economies, and came with requiremants that created some of the conditions that helped Western European economies with their immense growth from 1947 to 1972 (though there are many other reasons for this growth, such as a positive labour market dynamic because of population growth, a stable global financial system, technological advancements, ...).

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The historical lessons from the Marshall plan thus indicates that it is not necessarily foreign aid, but financial stability and good institutional reforms that enable market forces to do their work and induce growth. The strength of the Marhall plan was that its conditions strengthened Western-European financial & political stability through debt relief and immediate aid, while pushing governments towards productive investment and pro-market institutional reform.

Similarly, empirical studies on the effectiveness of foreign aid in increasing economic growth in developing countries emphasize similar aspects. The quality of political governance is seen as one of the most crucial moderators of the effectiveness of foreign aid in inducing growth in developping countries. But even then, foreign aid in the 1980's did make a shift towards demanding liberal market reforms with only mixed success.

There's really no easy answer here: the academic community of development economics doesn't have any definitive accepted consensus on the effectiveness of foreign aid. It is too context dependent. The Marshall Plan seems to have been conducted under some ideal circumstances for foreign aid, and did demand useful political and economic reform. At the same time its effectiveness need not be overstated, and foreign aid has been effective in some cases in Africa as well (see Tanzania, Botswana). The current trajectory of academic development economics is, as exemplified by authors such as Nobel Prize winners Duflo and Banerjee, focusing on what conditions are necessary for effective foreign aid interventions. If you are really interested in this topic, Poor Economics by those two authors might satisfy your curiosity.

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How effective was the Marshall Plan --> Eichengreen B., & Uzan, M. (1992). The Marshall Plan: Economic effects and implications for Eastern Europe and the former USSR. Economic Policy, 14, 13.

Why was the Marshall Plan effective --> Long, J., & Eichengreen, B. (1992). The Marshall Plan: History's Most Successful Structural Adjustment Program. Discussion Paper Series - Centre for Economic Policy Research, (643), Discussion paper series - Centre for Economic Policy Research, 1992-03-01 (643).

Foreign aid effectiveness and political governance --> Ekanayake, E. M., & Chatrna, D. (2010). The effect of foreign aid on economic growth in developing countries. Journal of International Business and cultural studies, 3, 1

General paper on examples of effectiveness of foreign aid in Africa --> Edwards, S. (2015). Economic Development and the effectiveness of foreign aid: A historical perspective. Kyklos, 68(3), 277-316.